Small round file for the holes. Do you think the center adapter fitting does all the work sealing the OD of the plate against the block? Think about what happens when you screw the filter down on it.
No I don't. Mine leaked less when I tightened the oil filter a bit more...but it still leaked, and the oil filter was over tightened compared to what I normally do.
I'm just passing on information I've gathered here and on B bodies, coupled with my own experience. Hopefully so others don't have to spend a few hours under their car fixing theirs.