Raid pass, once a day? or?

You can get a free pass from today then use it tomorrow and get another free pass that day, I have done it manny times.

Yes, you can do that.

I raid the boss with yesterday's, then I go to another gym and spin for the 2nd pass (today's). There are a crap ton of gyms near me (especially by car). Every church, 3 in every park, 1/5th of all restaurants, random fountains, etc

Yep, do it all the time. That way I only feel pressured to off a level 1 or 2 every other day just to make sure I use the free one. Keep the two freebies for Saturdays when I can plan out my level 3 and 4 targets.

You can even spend yesterday's pass on a raid, leave the raid, spin the gym and get another pass, and then go back to the raid. If you wait until after you win the raid, you can't spin the gym anymore, and if gyms are far between, get today's pass now, not later.