[GTALUG] Modem/router replacement?

I have been using the same DSL modem for ages (I think I might have bought it from iStop), and it continues to work pretty well. However, because it has a router in front of it, whenever I have a problem tech support wants me to plug it directly into my computer and run the PPPoE from there to eliminate the router as the source of the problem. A brief, magically resolving problem over the weekend has brought up two things that I would like to know from the list's vast knowledge. 1) How do I run a PPPoE connection from Linux, preferably from the command line? 2) If I want to buy a new modem as a spare, do people have recommendations, and should it include a router? Thanks!