Después de haber desbrozado algo más el reglamento y echarme unas cuantas partidas más, me respondo a mí mismo con las conclusiones que he creído correctas tras leer hilos en BGG, por si a alguien le sirviera de ayuda.
1.a.SI
b.Jugar hechizos potenciados con maná blanco o verde
2.a.SI
3.No es inmune porque aparece las palabras Attack X, Block X, sin embargo son ineficaces (valen la mitad).
4.Correcto
5.Lo conseguí
6.Fenomenal post en BGG con interesantes consejos:
Let's collect some solo\coop strategy advice.
Here's what I've figured out so far:
Fill your unit slots - try to get all your unit slots filled when possible. These are free power. Get some gold units if possible. If you don't have a lot of influence, consider picking up Call to Arms if it's available - casting that on two nights can get you two great units. The level 4 units are exceptionally powerful - if you are getting a free unit from ruins or from call to arms, try to wait until gold units are exposed if it's feasible to do so.
Reputation is a resource - it's okay to spend it. If you're having trouble powering up, maybe that artifact you get from burning a monastery will help.
Adventure!: Ruins are great - you can use your units and the enemies are not fortified. Lots of them will give you good rewards - artifacts, spells, maybe even gold units. In a solo\coop game, I only do the mana ruins when I need the 7 fame in order to quickly level up. I don't bother with them late-game - they're not helping you hit the cities. Dungeons are not so hard - with a spell or some advanced actions you can take out most brown enemies, and a free spell or artifact is a great reward for the early game.
Easy on the keeps: Keeps are not that hard to assault, but you don't actually get a permanent reward for taking them. It's good to break into one if you can recruit some nice keep units, but I'd watch out for loading up too heavily on keeps otherwise - unless you can find a keep near a city, you won't be able to leverage the keep card draw in the endgame. Mage towers are preferable to me - another spell in the deck is always good.
Tech up, burn down: In the later game there's a rhythm of building up resources and then burning them down for a big attack. It's okay to break those artifacts if it gets you a city. Burn through your crystals and wound your units if you have to. Prepare for those big turns by crystallizing mana, buying units, hitting ruins and spawning pits in order to get a crystal stockpile. Maybe you pillage a village. There's no prizes for ending the game with a high reputation score.
Use the cheatsheet: Before you go into a dungeon or ruin, you can look at the back of the rulebook and get an idea what kind of enemies are in there. Maybe you don't know what's there, but you know your hand can easily kill 3 of the 4 possibilities - it's probably worth going in. If half of the possible draws are going to wreck you with attacks you can't block or afford to absorb, maybe you come back later.
Prepare to attack the cities: In a solo or coop game, you know for sure that you have to hit a city in the endgame, so you know you're going to be coming up against fortified city defenders. From the cheatsheet you know that they have lots of resistances and lots of elemental attacks - find some ways to deal with this. I swear by Expose, but there are other good options. Just keep your eyes open for them in the offer, especially the spell offer.
Take some wounds: - It's better to take 2-3 wounds and clear a site than to wait for the next day. If you're not taking a wound or two, then you're not using the full power of your tranquility and the magic glades. If you can trigger a orc or dragon fight while on a glade, you can even get the free heal at end of turn - sometimes taking the wounds to hand and then using tranquility\glade is substantially more efficient than trying to block.
Get some movement: - the core tiles are full of swamps, lakes, and mountains. You will want some extra movement to make it through the midgame and to set up your final assaults without having to blow your whole hand. I love to pick up Pathfinding if it's available, but if you can't get that, there are lots of other good options. I love Ambush and Agility, but almost all of the movement powers are good in some way. Refreshing Walk is a nice way to get a little extra healing in your deck. Wings of Wind is good for fixing any movement problems too. I usually end up casting it at night to get across some mountains.
Pacing: In my ideal solo game I'd be hitting city 1 on day 3 and then I can spend all of night 3 hitting city 2. In practice I can't always pull that off - sometimes I need to hit them both in night 3 if I don't have enough good stuff yet in day 3. If you know that in night 3 you only have to take one city, then you can spend some time setting up the assault or massaging your hand to get the exact spells you want and getting in the perfect position. I like to use my movement points to get right up next to the city (maybe even in a glade next to the green city) so that you get all the movement out of your hand (except for the one you need to do the assault!), and you also get to reveal the garrison. Hopefully you can then look at your hand and figure out if you can take the city.
Try, try again: It's okay to assault a city twice if you can only take out half of the garrison on the first go.
Know your strengths: Where possible, try to line up your mana production with your mana consumption. If you've got mana artifacts or mana character skills, try to match those with the spells and unit abilities that you're using. Arythea can turn wounds into red and black mana, so then maybe you can afford to buy more red spells or fire golems. Norowas has skills to generate white and green mana, so you know you'll be able to cast those spells no matter what the source rolls for you. Don't gain the character skills that give +1 siege attack unless you've got some siege powers to stack it with. (catapults, golems, spells, crushing bolt)
Figure out your endgame: I've come across two main strategies for dealing with the endgame - you're probably either going to go heavy ranged\siege or heavy attack\block. If you're going ranged\siege, then you need multiple ranged attacks, and you probably need expose or tremor in order to remove fortifications from the cities. If you go this route, you'll break down the fortifications and then kill all the enemies with ranged attacks so you never have to block. If you're not going this route, then you're probably going for heavy attack power (flame wall, blood rage, stuff like that) Since you'll have to block before you can attack, you'll need either big blocks, or things like whirlwind and wings of night to prevent attack phases. Be careful mixing these approaches - picking up a few ranged attacks without expose\tremor to back it up will just make you sad when you assault the cities. A few ranged attacks are never bad - you can use them to take out ruins and dragons and such, but be aware that they aren't fully effective against the cities without some other support. Be wary of leaning heavily on blue and red spells for your endgame blockbusters - fire\ice resistance on the city defenders can ruin your day.
Easy on the healing - This is just my personal experience, so maybe somebody can counteract me. I have had trouble finding a way to use the really powerful healing spells. If you are planning to wound your units and then heal them, then you've stopped an attack, but you've also lost the opportunity to activate the unit in the the battle. You want to have the big healing spell near the fight time so you don't spend a ton of time covered in wounds, but you don't want it during the actual turn that you do the fighting, because it's a dead card during the fight. For these reasons I haven't been able to get a lot of value from the healing spells or the regeneration action as compared to other more active abilities - maybe you guys can tell me what I'm doing wrong.