BS”D
As for cream of tartar, here is what Rabbi Levy A”H, the founder of the OK, has to say on the matter:
http://www.okkosher.com/Content.asp?ID=167
Given how readily available cream of tartar with a hechsher was the last time I checked in the US, it seems that most or all of it is kosher as you can’t possibly get commercial quantities from kosher wineries. Either that or it is no longer made davka from wine leftovers.