A rule of thumb for loose bearings is to fill the race entirely, then remove 1 ball. This leaves you with what Duragrouch described in the post above for quality cages. I've been practicing this for about half a century,. It seems to work.

Marine grease - brand doesn't matter. I've never used (or seen) the Sta-Lube grease and have used marine grease both from similar tubs and grease gun tubes. Given how modest the demands made from the enormous horse power developed by quadriceps (yeah right!) vs hours of 70 mph highway speeds, then plunging that hot hub in cold salt water, I don't think our modest little ball bearings care whether you spent $6 for that tub or a gazillion.