External SATA-drives, extra RAM, etc.?

Hi,

I've got an old MacPro which soon has to retire. Been thinking about getting a Mac Mini and would be happy if you can shed some light on a few issues:

1. I have two SATA-disks and one SSD. I have figured out that the SSD can be installed in a Mini. But what about the SATA-disks? Since the SSD is 1Tb and one of the SATA is too (used as backup through Time Machine), and another SATA (with Mac OS X) is used when maintaining the SSD, it's pretty important that I can use them. How can I solve that without spending too much?

2. I have 12Gb RAM in my machine now. Can I add memory to a Mini? If so, which editions?

Thanks a bunch for help...

Dan