1) loaded question man
"man route" and have fun
2) "netstat >> targetfile" will appeand a netstat to the file, or "netstat > targetfie" will overwrite the file with the current output. you can setup a cron job to run this however often you want. "man crontab" It looks complex but cron is pretty easy.
3) you want to use iptables to do that. Do you mean port forwarding or ip masquerading? you can do both with iptables. Take a look at some preconfigured firewall scripts I use firegate, that does NAT and port forwarding for my network at home. Search this board. for firegate, I've mentioned it in a post in the past, and some other guy made a post about another one that are was easy to use...
At any rate you can get firegate from here...
http://sourceforge.net/projects/firegate/
Just some ideas