Dry, but my machine came with a serrated wet trim blade. I'd do it very very fresh or it'll be a mess.
I use smartpots (fabric), and yeah, there are a lot of advantages (also, it may not be legal for you to plant in the ground). Better drainage, can flush nute locks easier, almost impossible to over water, no naturally occurring soil pests, and the roots air prune for increased branching and better nutrient uptake. Increased root branching also means good water conservation and no root binding.
SeaGreen should help with water utilisation as well.
I started with seeds in Feb last year and my biggest plant was 14' tall x 10'wide. Make sure to give yourself room if you use 100-200gal smartpots. You need at least a few feet of clearance around each pot, just for the plant. You'll have so much weed you won't know what to do with it all. I suggest diversifying your girls into 5-6 diff strains if you do it that way so you don't get sick of the weed, hehe. Another advantage to starting beans that early is culling males earlier. I think your rack is big enough for that early, maybe. You might have to use your grow room.