I think that you have a pretty good handle on both questions
You should always use a rod heavy enough to land the largest fish that you're like to catch, otherwise it comes down to 'straight lining" the "too light" rod and using the reel as a winch, or hand lining the fish in.
As for the surf, you use the breaking waves to your advantage. As they break on shore, you clamp down on your line and back up, using each wave to help propel the fish up the breach. As wave recedes you do your best to hold the fish in position until another wave breaks and you can back up some more. You do this until you feel it's safe to bend over and grab the fish, never turning your back to the breaking waves.