Hello eggy :)
First of all, thank you for your support, I appreciate it a lot !
Of course you can edit, modify, switch colors and so on ! You can also use them for personnal AND commercial project (I appreciate the credit !).
You DON'T HAVE to pay me with a % of your game revenu, keep everything for you :) !
If you can't afford every packs, let me know, I'll send you some download keys. Have a good day !