Will do.
Regarding entities, is it possible to have a creature with a caste that doesn't utilize professions while other castes do?
What do you mean with "utilize professions"? Gain profession skills? Use custom profession names? Be able to have labors set? Be able to work in a profession?
Being able to work in any profession.
The permission to work in a profession is determined by the [PERMITTED_JOB:] tags in the entity, it can't be changed per caste. But you can change the learning rates and skill rust rates per caste and skill with [SKILL_RATE:], and even give a caste natural skills with [NATURAL_SKILL:], so you could theoretically make a caste that will never ever be good at farming, for example, no matter how hard it tries.
Is it possible to create creatures from workshops? Here's what I've tried:
[REACTION:MAKE_A_ZOMBIE]
[NAME:make a zombie]
[BUILDING:GATEWAY:CUSTOM_Z]
[REAGENT:A:1:CORPSE:DWARF:NONE:NONE][ROTTEN]
[REAGENT:B:5:MAGIC:NONE:NONE:NONE]
[PRODUCT:100:1:CREATURE:ZOMBIE:NONE:NONE]
[SKILL:ALCHEMY]
When used, it takes 6 random objects (instead of 1 dwarf corpse and 5 of the metal bar I added) and then crashes when the construction would be finished.
Edit: I realize what the problem with the "magic" bar was, but how would I do the corpse?
First, your reagents should look like this:
[REAGENT:A:1:NONE:NONE:NONE:NONE][USE_BODY_COMPONENT]
[REAGENT:B:5:BAR:NO_SUBTYPE:INORGANIC:MAGIC]
Second, you can't create creatures with reactions. There are workarounds to that (create an evaporating stone with a syndrome that makes the worker temporarily transform into something that loses a hand and can reanimate and transform that hand into a different creature), but they are messy and unreliable. I don't really have a link to a post describing that, maybe someone else can provide one.