When I have used store bought probiotic cultures I have opted for one in liquid form which to me makes more sense that it would contain an active culture rather than something in a pill. I can't back that up with any facts just a matter of personal preference.
Kefir is sorta like a liquid yogurt in texture and taste and it is a lot less mucous forming that yogurt. Like I mentioned before that it contains a more diverse number of strand of beneficial bacteria than yogurt.
I have never seen Rejuvelac sold already packaged but if I recollect correctly it is made by soaking wheatberries and maybe something else and the liquid is the Rejuvelac but I'm not 100% sure on the ingredients. LNDolls uses it and I'm sure that she'll be glad to give you the recipe.
The cool thing about Kefir is that it can be made from other liquids besides cow milk. I have had it made from coconut milk and it is quite tasty. There is a Kefir forum here on Curezone that I'm sure you'll get lots of good info on it there.
As far as what you ate at the BBQ I'd say you're just fine. I love to make portablello sandwiches. My toaster oven crapped out on me but I would take a nice big cap and cover it with Tamari and some olive oil and broil in the toaster oven. Add some sunflower sprouts a little vegit (veggie salt) a dash of balsamic vinegar some mustard and voila a nice quick easy sandwich.