Since your ground is currently on the cold and wet side, a good fungicide would be advisable, maybe even a fungicide combo using 2 different fungicides. I don't know if you run enough risk of early bug problems there, that you'd need an insecticide in the mix, but if you do, an insecticide is definitely beneficial, and worth considering. Most seed treatments are somewhat systemic, and will give you some protection for a while after the young beans are up and growing.

You have ground that has been in corn for several years, plus ground that has had/currently has, problems with being waterlogged. Inoculant would definitely be advisable, and probably the double rate that is normally called for under such circumstances. Either seed applied with the seed treatment, a planter box treatment, or better yet some of both. A normal rate in the treatment, and a normal rate in the planter box, which would give you your double rate. 

Hth,
JDH