I have a job and a family, so I don't have too much time to play games.
I played the original game, KBTL, only once, with a paladin on impossible. I have yet to finish my impossible warrior game in KBAP. But since it seems that there would not be a 3rd installment for the KB series, I might play mage on impossible when I get the time.
I also play the game at impossible/7-days/no-loss, so coupled with my limited playtime, it's pretty slow going. Just like you though, I do have the advantage of benefiting from the experience of others, thus my choice of units.
Yup, all the enemies will try and attack your droids first, especially the repair droids. This is all good for this lineup since the droids can easily repair each other. Eviln may be overpowered, but I still sometimes find it tedious to bring back lost undead units with it.
Take note that for most battles, it is probably better to just let your droids, bone dragons, and phantom bone dragons to do all the fighting and just let your black knights kick up their heels and relax. This is because they are slower than the rest of your units, and in the middle to late part of the game, an attack from an enemy stack would most likely cause them to incur at least some losses, thus necessitating a casting of Eviln. Their superior firepower is vital for boss battles though, so don't make the mistake of thinking of them as unnecessary.
In this lineup, it is important to note that the shard from Moro Dark is not really needed; just kill the fool for XP.
For the initial islands it really helps a lot to do a lot of digging with your pet dragon, and hopefully dig up a Call Colossus. I was very fortunate to have dug up 4 Call Colossus by the second island (Scarlet Wind). I took out Bolo quite handily by using 2 of the 4 Call Colossus scrolls to generate 1 red dragon and 1 black dragon. To prevent the droid hero R-14 Gromozeka from pounding the red dragon with direct damage I simply took guard droids and repair droids to fill in the rest of my army slots.
Note that if you are trying to go for dragons via Call Colossus early in the game, you need to prioritize Glory (from the mind tree). Even a warrior would be hard pressed to get 2,000 (for red dragon) - 2,500 (for black dragon) leadership by the 3rd island (Bolo). In a 7-day run, it pays off though, as evident by my taking out Bolo in the first pass, before going to Verona.