you've got yourself some nice Cisco hardware to play with. Even if a bit old. I hope you have all the documentation that goes with them.
Redhat is fine, used in many servers.
Ubuntu / Debian manage networks a bit differently, mostly different files, different syntax, different configuration tools.
But the network theory remains the same.
I suggest you get yourself some trendnet USB to RJ45 adapters to make your laptop have multiple network interfaces (will make your life easier to connect to those multiple networks and just costs about 20$).
Very good resources to read are: