They work just like any other network connection. Just make sure the network addresses are compatible (same subnet, mask, etc) and you should be able to communicate between them with no problems.
As for servers, it is the same as any other network connection. If you want to ssh from Comp A into Comp B, for example, A needs to have SSH client and B needs to have an ssh server running.
Newer ethernet cards (and all GBit Enet cards, I believe) autosense so you may not even need to get the special crossover cable.