Touch IC reballing questions

Hey all, a few questions as I’ve recently started reballing IC’s:

1) Is it important to have all the balls on the touch when reballing? sometimes I miss 2 or 3 balls, is that a big deal?

2) On the soldering board, is it required I clean all remaining solder residue off the "ball joints" so to speak on the board? If so, what should I use? I tried using a tinned soldering iron tip but it kinds of just spreads it out.

Let me know, thanks in advance.