Begier question about digital snakes

I am trying to buy a complete setup with a SL III console and a digital snake. After a hours of searching i couldn't find

1) if RML16ai is compatible with SL III

2) Do i have to buy something else to coect SL III with RML or SLIII 16R

3) Is it possible to use SLiii 24R on SLiii 16 and have 24 usable chaels

4) if i could use digital snakes other than presonus and if you could name some of them.

Thanks in advance.