I might be interested in helping.

1. What is your expected timeline to get this working?

I would prefer for it to be ready for Debian 8.0 (not a requirement)

2. Is there enough support in mainline to at least boot the board to a linux console?

Mainline has some support for it, yeah, (but not for sound) Linux mainlining effort http://linux-sunxi.org/Linux_mainlining_effort

3. If so what kernel?

The system officially supports Linux-Android kernel 3.4, which has all the drivers built-in and open-sourced (but sound driver is crappy there)

Lubuntu Desktop/Server SD Card Installation for Cubietruck: http://docs.cubieboard.org/tutorials/ct1/installation/install_lubuntu_deskto...