there are several problem there,

you have wrong kernel power packages installed, you have to download them manually from garage and then install them manuall one by one with:

dpkg -i packagename.deb

You have installed kernel power 52, so you need same version for bootimg and flasher

Then you seem to have installed CSSU, but you don't have the proper repository enabled, see you error for micro-b

And sorry, but i can't help for the rootfs free space, try to uninstall unneeded softwares. But my knowledge there is very limited (for now), better check the wiki again.