1. You can not create Cloth for Character Creator character now, please wait CC 1.5 version.
When we release CC 1.5 version, you can create your own clothes.
2. You can add softcloth to any prop or accessory. However, you only can use softcloth setting on plane or one face mesh. You can not use on cube or close mesh.
3. You can attach any objects to standard character model in iClone6.
You can find some tutorial in Reallusion youtube channel.
Like this one to teach softcloth setting:https://www.youtube.com/watch?v=nek-bFtpoMs