Hello!

How many cryptos is hard to list specifically but anything in the Top 20 on coinmarketcap along with their forks. So all ERC20 and all Masternode coins are included too.  The pairs don't have a limit. My only recommendation would be not spread yourself too thin. It's hard to keep a liquid market in obscure pairings. Even larger exchanges have problems there.

Feel free to send me an email eric@infraexdev.com