Whew, good luck! Those are some decent setups and take a bit of time... You could also hunt down an RPM I'm sure though, maybe even use synaptic to get it all running, that'd be nice
Then follow it all up with a webmin setup for admin to it all. www.webmin.com
And synaptic can be found at www.freshmeat.net
As far as the 2 Lan cards, possibly, depends on what you have got and what you will be doing as far as what machines and hardware will be doing what.
If you've got a standalone router, such as one from d-link or Linksys or Cisco, then no, you shouldn't need 2 LAN cards, however if your linux box IS going to be that router or something like it, then yes, you will likely need more than 2 though, something like 1 plus the amount of computers that will be running through it. Unless of course it's even more complex, in which case it will take more than just that, or even possibly less. Really depends on how things will be setup.