Southwest Iowa, I am not sure what to recommend to you.  There are about three major companies that sell most soybean inoculant although there are many good inoculants.  I don't know which to recommend for your farm.

https://www.google.com/#q=soybean+inoculant+trials

In Ohio and many states, ABM's strain are number one and are very hard to beat, although I am sure Jim Pullins has a good one.  Ag Talker Jay Herron markets a good line of inoculants on www.innoculant.com

https://www.google.com/#q=best+soybean+inoculant

On your second question, I do not know the answer at all.

Ed Winkle