I was wondering what happens to all the credits in my clan if I decided to close it. Do I get them back?

No, if you close your clan, the credits will be lost.
Better is to build it up.
We are planning to build a feature that serveral clans can join together to keep at least some of their credits.
But right now they go to Nirvana.

how do you get the icon and logo? where do I go to download or buy icons for this and how do I do it?