I have one, and use it a lot. I replaced Xandos with straight Debian, and added 1GB of RAM, and a 16GB SD card (the latter two increasing the cost, a bit). It is a great size, since it can be carried around quite easily. I don't know about the modem. Best to do a search to see if it is supported by the OS you will be using. The wifi works fine for me.
Best wishes,
Bob
PS
RLF