Intro
Greetings, all!

I made this post due to wanting to understand how certain mechanics work in Wizardry 6 & 7 since our group is scheduled to play Wiz6-8 with the same characters.

Casting
C1: What ddetermines the maximum power level of a spell a character can cast?

C2: What skill/class level/etc. determines what spells a character can learn from leveling? From spellbook use?

C3: Aside from Heal Wounds, Armorplate, Enchanted Blade, and the status removal spells, what spells from each spellbook (Alchemical, Arcane, Divine, and Psionic) are most recommended for a group to have?

Multiclassing
M1: If I swap classes away from a class then back to that first class, does that character get his EXP back? His stats?

Exporting to Wizardry 7
E1: What party setup is best to have at or near the end of Wiz6 for transferring to Wiz7? I've heard that having an all-elite group (Ninja, Monk, Ranger, Samurai, Lord, Valkyrie) is generally a bad idea.

E2: What spells transfer?

E3: What is the maximum skill amount that transfers?

I can answer these questions:
C1: Your level and the level of the spell. In particular, the difference between the two must be at most 1, so to cast a level 6 spell at power level 6, you must be at least level 11. (Note that your level will decrease if you class change.) Exception: If you know a spell, you can always cast it at power level 1, even if it's a level 7 spell and you're level 1.
C2: Only the spellbook skill (Thaumaturgy, Theology) matters, provided you're in a class that can learn that type of spell, an for hybrids, that you are high enough in level to learn the spell. Bishops are a special case: At any given level up, a Bishop has to learn either a Mage or Priest spell, and which type of spell learned depends on whether the new level is odd or even. Note that spellbook skills do not increase from use. No, but you do get to keep your skills. This means that, if you change back into a spellcasting class, you can keep learning new spells from where you left off (and the lower levels go by quickly, since you're level 1 again). Unlike earlier Wizardry games, you will have stats high enough to meet your new class's minimum requirements after class change (in Wizardry 1-5, you got the racial minimums, so you don't meet your new class's requirements after the change).

dtgreene: Thankee!

Math Stuff
M1: What are the formulas for ability points (17 STR vs 18 STR vs 20 STR, etc.)?

M2: What does each point of a weapon skill do?

M3: Beyond qualifying for certain spell power levels, what does each point of each magic (Theology, etc.) skill do?

M3: In W6 and W7 you get +1 to the mana pools at level up for about every 40 skillpoints in the caster's magic school.