Hello Paul,
Yes, there is indeed a plethora of glue types and glue brands out there, but most actually can be reduced to a reasonably limited number of types of glue. For instance, as I'm sure you are aware, there are four main types of CA glue, namely thin, medium, thick and gel, which all have their areas of use. Personally I mainly use thin (which is my go-to CA when it can be applied by capillary action) and thick (which I find more useful whenever the glue must be applied before the parts are joined together), but for certain applications medium or gel come in very handy, too.
As for the specialist caps, again, yes: there are two aspects of these to which care in selection needs to be applied. Firstly, of course, one must make sure that a cap that should go on the bottle/container actually fits said bottle/container, and secondly the cap material should ideally not be glueable with the glue in question (for example, CA glue does not stick to the plastic [silicone?] material of which the Zap Flexi-Tips are made), so that any precision nozzle or opening does not get clogged with glue straight away.
Mattias