Questions

Yes. CC is mods. There's Cc for everything just go searching google for "sims 4 cc" and a subject, like freckles or summer looks and find the things you like best... as to the poses... You're looking for Andrew's Poseplayer and the teleporter associated with it. Which is somewhere on this forum. You would need those and then a "posepack" from anyone you like that makes pose packs. The pose pack requires you to place teleporter statues in a special spot, say a middle of a chair/couch...and then you use the poseplayer to access the pose pack and then it puts the sim in a particular pose for a time and then you screenshot how you want. There are different kinds, some that scroll through several poses in a row at a time, ones that do entire animation scenes and ones that do singular poses for a particular scene and then group versions that require posing multiple sims at the same time.

The one thing you may have issue with that if you pose multiple sims in a setting and mess up say the last pose... all of them will reset if you place another teleporter down. so you would have to start over. Also look into deco sims, these are pre-set sims that are like statues that you can fill in your scene without having to pose everyone.