domain mapping installed...what now?

so i just installed the domain mapping plugin on my multi site.

a few questions...
1. is there an extra plugin i can install to add the same theme to these external domain names ill be adding?
2. will i still be able to control these "mapped domain names" the same way as any other regular multisite directories?
3. im a little unsure on how to add my external sites now that i have installed the domain mapping on my multisite.