A: Yes, 99% are completely free. Some authors link to Patreon for early access, but the stable release lands on GitHub for free eventually.
Before touching GitHub files, copy your HoneySelect2 root folder. Mod conflicts will happen. honey select 2 mods github
Many GitHub repositories are dedicated to porting clothing from other games (DOA, FFVII, Cyberpunk) into HS2. Look for repos with .zipmod files. A: Yes, 99% are completely free