Staves and alternate caster types

[EvilMinion]

Does a caster need to have all the spell a staff is capable of casting, on his spell list, to use the staff?
Or if he has any of them, he can use all of them?
Or can he only use it to cast the spells that are on his list and the rest he can't use?

Some staves seem to require level dipping to make full use of.

For instance, a Staff of Defense... is there any straight caster that can use all of the spells in it? (shield and shield of faith are typically mutually exclusive on most spell lists)

[LazarX]

A caster can cast the spells on his lists and is SOL on the other spells short of using Use Magic Device.

Presumably the Staff of Defense is created by multi-class Wizard/Clerics.

[Dragonchess Player]

For the most part, you have to have the spell on your list to use a staff to "cast" that spell (per spell trigger item rules). However, if you want to be able to fully use a staff of defense but don't want to bother with Use Magic Device or multiclass, there is one other option: half-elf cleric or oracle with the alternate racial trait Arcane Training (Sorcerer or Wizard). "Arcane Training: ... Half-elves with this racial trait have only one favored class, and it must be an arcane arcane spellcasting class. They can use spell trigger and spell completion items for their favored class as if one level higher (or as a 1st-level character if they have no levels in that class)."

On the negative side, you give up any favored class bonuses to get the ability to use any staff, wand, or 1st-level spell scroll in that arcane class without Use Magic Device checks.