I haven't tested this but something tells me we should also use a direct child selector and any remaining tag names in this path to avoid selecting stuff from other nested tables.
That sounds like a good idea. Go for it.
Done in r101420.
I think we may have this bug. It is applied to 1.18wmf1, but left out of 1.18 beta release (because of follow-up?). Please submit either this or the follow-up r101420.
It is already tagged as 1.18, it is scheduled to be applied to 1.18. It apparently didn't get into the first beta but unless a different decision is made this revision will make it into the second beta or eventually the stable release.