Spells and Spell-Like Abilities and Prestige Classes

[badgerman]

I'm a bit confused about the handling of spell-like abilities when looking at the prerequisites of prestige classes and gaining levels in a spellcasting profession.

The class factotum for example gains an ability (arcane dilettante) which allows him to cast spells as spell-like abilities so technically it's no spellcasting profession as arcane spellcasting or divine spellcasting. Nevertheless the factotum gets an arcane caster level.
So a level 13 factotum could meet the prerequisites to enter the mindbender class or a level 5 factotum the daggerspell mage class for example.
But does the progression in a spellcasting class, through gaining levels in these prestige classes, affect any of his "spells known", "spells per day" or arcane caster levels ?

Same with the warlock. Doesn't a warlock gain new invocations when taking levels in a prestige class which grants levels in an existing arcane spellcasting class?

I am a bit helpless to tell my players what they are allowed to take and what is not allowed.

[Chronos]

The warlock gains new invocations from such prestige classes because warlocks have a specific rule that says so. Dragonfire adepts have a similar rule, which also gains them increased damage on their (Su) breath weapon. Nothing specific is said about factota having a similar rule, though. A DM might rule that the warlock gives a precedent that the factotum should work that way, or might rule that the absence of such a rule, even though it was explicit for the warlock, was deliberate.

As for prerequisites, spell-like abilities are good enough for meeting caster level prerequisites, as well as for ability to cast a specific spell (thus, for instance, if a PrC had "must be able to cast Detect Evil", a paladin could qualify). But they do not meet prerequisites of the form "Must be able to cast spells of X level", even if they mimic spells of that level.

[badgerman]

Thanks a lot

[Darrin]

I believe it works something like:

Requires a specific spell, such as mage hand or charm person: SLA qualifies.

Requires a specific caster level, but does not specify spell levels: SLA qualifies (if CL is not listed, CL = HD).

Requires a specific spell level, such as "3rd level spells": SLA does not qualify.

(I think some DMs are "flexible" on the last point.)