You'll need a multi channel sound chard to connect your hardware synths so you can record them one by one on separate tracks or, you can have a simple soundcard but you'll need an external mixer to connect your hardware synts.
As for midi, it works the same with SS or hardware, you just need to route the midi to the right place.
If you have more than one hardware synths, you'll need a midi patch bay to have controle on all of them.
