They're not "already forwarded". If you make an outgoing request your router allows the response to get back to you. Set up IIS on port 80 and see how fast someone outside yor router can connect to it. You're getting
out on port 80 (or you wouldn't be here), but no one can get
into your port 80 from outside unless you forward it.
In order to get an incoming request you need a proxy server (an intermediary site), which turns the situation into your request and the other person's request both being outgoing to the server, or you need to forward the port to the computer that's listening on that port.
Most bit torrents run in either one of two modes. If you can listen you get faster downloads. (Share and you get rewarded.) If you can't listen you can still download, but your speed won't be blindingly fast.
But in most situations, the only router you have to forward ports on is the one you're connected to - wired or wireless makes no difference. You may have a problem if your modem is also doing address translation, but that's still a local problem and easy to solve.
http://www.portforward.com/english/r...outerindex.htm is the place to go to see how to set your particular equipment up for your particular port(s), or go to their forum (link at the top of that page) and post a question.