[Oversway]

1. I'd say smaller armies of expensive troops... but a hybrid of the two may be the best.
2. For an immobile its mostly research (especially early on). Later summons and/or artillary spells, and depending on your pretender, movement spells (and possibly battles)
3. Not often, usually just to get to a level where I can forge items that boost spell paths.
4. Increase your income and research. Acquire lots of high hp commanders with high protection and life draining weapons (SCs).