The intersection thing just came to me as I was writing that up. The trick is to go out and practice or race enough that you can get through this without having to think about it. It's often harder for me to write it down than to do it on the water; which is a good thing, because with the closing speeds we have, you don't often have too much time to think about who has ROW.
Gates? The nice thing about racing the Wave, you go around the weather mark, stay on starboard, and head DEEP, directly at the left gate (looking upwind). The only boats that you need to worry about are the ones coming at you from your port side (either boats coming upwind on starboard, or boats going downwind on starboard, at a higher angle; although the latter normally sail around you as a speedbump). Anyone coming at you from your starboard side is on port...
EDIT 1: You can tell that Matt and I spend a lot of time on RC. The gates are ALWAYS discussed relative to course axis (looking upwind).

EDIT 2: You haven't seen a "crowded" gate until you've sailed a H16 NAs, in 25+ knots of air, with no less than 2-3 boats capsized and floating toward and through the gate (at all times) in a 60+ boat fleet. Good times!!!
Mike