could the CO tank be in the same hex as the assaulting friendly infantry (necessary to give LCR bonus) but not participate in the assault itself?
I thought ground troops could only enter an enemy-occupied hex to assault.
That is correct.
If not assaulting, the CO tank could not enter enemy-occupied hex and could only give RRR bonus from nearby hex is that right?
That is correct. I was quick to answer and I was wrong. Will edit/update my previous post.