Ok, issue a) will hopefully be resolved with the new device. Note it has the same chipset as Trendnet's.

Issue b) was caused by the local network not having a DHCP server, so who knows where I was getting the DHCP packets from, and what was in them. I tried on a third LAN then, and it worked, except again I had issues a) and b).

Issue c) remains elusive. It seems here that Maemo applications dislike usb ethernet, so I am thinking of installing a dummy network as suggested there. Indeed, it seems like that would completely convince Maemo that I am connected to a network. Never done that, though. Tips, please?

@biketool, yeah, I don't really need need it, but there is a coolness/nerdiness factor involved. Also, once you do need it, it will be too late to try to make it work.