I would ask Ian about the pumping, I'd say at least a few weeks before, and months after. But that's my guess. If it were me, stop a month before, don't start again until 2 months after.
Far as the shuttle it's SUPER slick, it's a private car (likely minivan/small suv), might take an hour going into MX, 90 minutes coming back (they have it timed to perfection based on your flight departure time) with mild to moderate traffic. Getting into TJ is easy, but without the shuttle holy hell what an insane zoo getting back - the shuttle is worth its weight in gold. There are special passes for medical tourism that I guess they have to skip a lot of the lines at the border. They have one dude who grabs you from the hotel in TJ and takes you to the guy in the CBD who has the medical pass and you change cars, then you head towards the border checkpoint and there' s a ramp he gets on that's specifically for medical travelers, so you're just cruising past people on the MX side who are stuck waiting 4+ hours to get to the US side.
Also, if you're staying at the Grand, the breakfast buffet is the shit. On the 2nd floor i think? I initially got confused thinking it was that French joint on the first floor but nah...a dope buffet on the 2nd (or third) floor. Oh, ane there's a in the hotel, this isn't a sleepy Marriott.