With the launch of the Groups program. RPGStock is now a group. For those wondering what this means it would be a good idea to check out the Help&FAQ section on dA for more general questions about groups.
For more specific questions related to RPGStock:
I'm a contributor! What do I do now?
Just ask to become a member of the group and then when you've joined I'll upgrade you to a contributor. As a contributor you will be able to submit deviations directly to the gallery rather than having to send them through me. 
My question isn't on here or your FAQ or the dA FAQ 
Ask here and I'll try my best to answer.