I don't have much experience with brewing sour beers, but I have fair amount of knowledge from reading posts, books, etc.
1. With regard to Berliner Wiese, what is the experiential preferred liquid & dry yeast?
I don't think it matters too much. It all depends on the amount of yeast character you desire.
2. Anyone know where to buy food-grade lactic acid for less than $1 an ounce?
..but I would not use only this to sour a beer - http://embracethefunk.com/2011/08/15...-post-ferment/
3. How many months does lactobacillus truly take to “tart” beer?
Lacto does most of its work early on, in the first week. Brett needs aging, lacto does not.
4. Has anyone successfully “cheated” with lactic acid additions or acidated malt? If so, how much/ratio?
I have not tried it.
5. What are the preferred controls (temp, amount of bacterial cultures, etc.) to achieve a good tartness in minimal time when brewing Berliner Wiese?
My Berliner Weisse turned out well with lacto cultured from grain, pitched into warm(ish) wort 2 days before pitching yeast.
1. Which brewers yeast ideally first?
It depends. Some yeast character remains after it sours, but beers with brett might get more character from the extra sugars left after fermenting with a low-attenuating strain.
2. How long to wait before adding bacteria?
It's really up to you..you can add them at the same time. Definitely lacto first if you're using it.
3. Ideal temp for bacteria growth?
Lacto -90s. But any ale temps would work well for all yeast / bugs.
4. How to expose to right level of oxygen for bacteria?
Some people use an oak dowel through the stopper on their carboy. I wouldn't worry about it too much.
5. Any way to cease bacterial growth before botteling?
Heat pasteurization...difficult at home..
You should read:
...and probably other posts on their blogs.