ok for the first question don't be a women and just pull the clip away from the video card trust me it wont break, (actually don't blame me if it breaks.) just do it carefully
and for the second question yeah it should still work, along as your pc case is being kicked around or moved a lot. If you want you could stick some electrical tape with one side on the top of the memory and the other end on where he clip has broken. you also might be able to switch out the clip with the one from your old mobo.