for toolchain, you can try this :
https://releases.linaro.org/archive/13.11/components/toolchain/gcc-linaro/4.8/
for access to rootfs, best way is to make copy of /usr and /lib on your workstation using rsync
$rsync -rl <user>@<device-ip>:/lib .
$rsync -rl <user>@<device-ip>:/usr
this is a good tuto about building toolchain for target devices, it's made for raspberryPi, but it's same for CubieBoard ...
http://www.fabriziodini.eu/posts/cross_compile_tutorial/