Hi. Great to see that ppl are still playing this. I am playing on impossible warrior and I am in Montero/Verona at the moment. By the way. I dont kite for maps at all or use scanner. I dont reload battles either (except bosses if all goes south). This means that I restart my game from the start far too ofthen
I am no expert, but will try to answer your questions.
1. The main achievement to go for is the one that gives leadership after 10/30/50 battles with no loss. You should be close to 30 by now. This will make your army a lot stronger. Continue on Bola until you are strong enough to fight for a map.
2. To use wanderer spells, click on spells when not in battle. Then click at the bottom right of the spellbook to find the spells. Finally click on the spell you want.
3. The companion bonuses are automatic mostly. For some you have to talk to your companion (for example for training units).