b) I am also ashamed to admit that I accidentally snagged 3
Don't let it bother you. With so many pinks in the river, it is bound to happen with even the best of intentions.
To avoid snagging pinks, one technique (that is certainly not foolproof) is to observe how your float submerges. If it eases under slowly, and/or on angle, then generally (sometimes, maybe) the fish has just brushed up against your leader and setting the hook is just asking for a snagged fish. If your float darts under quickly then generally (sometimes, maybe) the fish is on the bait. Now these aren't truisms but generally speaking it works.
The key however is the angler's tolerance for risk and ambiguity. If you have a low tolerance you will set the hook at every dip of the float that you know isn't bottom. If you have a higher tolerance, and are tired of hauling in pinks sideways, you start to read what your float is telling you.
Another application of this technique is drifting little tufts of wool through the massed chums to get the the coho that are behind feeding on the loose eggs.