I also have an Apple Airport Extreme "N". Normally, I have the following on the wifi network:
-4 Apple computers
-1 N810 (with a SIP and a google talk account active)
-between 1 and 4 N800 (all with google talk accounts active)
-a Nokia N80 or E51 phone (sometimes with a SIP account active)

I don't experience reboots usually. Youtube works. I rarely use torrent, and never on the Nokias.

I did experience reboots once, while I was testing videoconferencing between one of the Apple notebooks and the N810 over google talk. I described what happened during the test here at the time.