What new collectibles can we expect?
Butterflies & Moths, plus a custom display to keep them in and an associated skill - Entomology.
There are two competition types (romance and baking). Can we customise our own competitions? Like for Spellcasters, crafters, bbq etc.
There are more than two, but those are the ones ties to specific skills. The other skill-based contests are more general ones.
Creative Skills Elimination (Teen+)
Child Skills Elimination (Child only).
Nothing vanilla for Occult XP or for skills other than creative ones (except for kids), though I'm sure modders will be on that, sharpish.
For your examples above:
You could do a BBQ specific one via the Cooking Skills Elimination (covers Cooking, Baking and Gourmet Cooking). You would just need to set up the lot with Grills instead of Stoves and set Grill as the Scheduled Activity instead of Cook.
Spellcasters could possibly do something with the Popularity Contest Elimination rule, if it's based on how they behave when using their spells. Only the nicest Spellcasters could win in this case, as it's based on increasing friendship, not increasing enmity. They might also be fun to play as (or against) in challenges with Motive/Relationship deficit Rules, and/or Player Choice Eliminations, things like Motive Games/Sul Sul Island gameplay. Like having a Vampire on Sul Sul Island in the trailer.
Can the group fitness class be incorporated into other types of fitness activities, like plumboomba?
Fitness classes can only be run from the new objects in this pack. No Plumboomba classes, unfortunately.