For your first question, Revival Tomes would be obtainable via special shops, dungeons, and quests. If at ANY shop at all it would be quite expensive.

Second question, there would be ressurection spells but they would be high level. I'm thinking of two ideas for spells: The Classic Move Tutor or buy some Spell Scrolls. And everytime you use a spell it gains 1 experience point. Example: a Fireball with 99 experience (or level 99) would be stronger than a level 50 fireball! But note, a level 99 fireball vs a level 95 fireball will be tough!

Last question, kind of both really, I would categorize spells by the following:

Elemental
Limited
Summoning
Traps
Healing
Passive/Support

I'll be making things like Custom Limited Item & Spells Applications. If you want maybe you can create a simple spellbook with a few basic spells to start out with?