Re: Humidity from treated lumber
OP is short for original poster (at least in my version of net abbreviations!). From your description it sounds like you are on the right track with the foam insulation. It may have been better to use it on the entire wall and not just between the flat 2x4's, I don't know if that will make a significant difference.
I have attached a link discussing basement insulation systems. It covers vapor and air barriers, good and bad systems. There is other research there that will probably be helpful to review.
You know your temperature and humidity conditions better than anyone else posting here, so you are the best judge of which strategy fits your scenario.