I would consider going a bit wider with the garage. You have two fairly wide vehicles to park, and it's nice to have a bit of room to open the doors so that you can comfortably get into and out of the vehicles without banging the doors into the wall or another vehicle. It's very easy for the third bay to get filled with tools and supplies---leaving you only a narrow aisle to work in.
I had a 36' wide pole barn built in SW Indiana about 8 years ago and it seems to be a comfortable size with a 18' wide door and a 10' wide door.
In SW Indiana, Daviess County Metal and Graber Post Building seem to have the pole barn market fairly well cornered--both for material packages and completed buildings. I think that they both subcontract the erection to independent Amish crews. They were very competitive in price when I had my barn built (I used DC Metal.)
The lack of building codes and regulations in some of the poorer counties in Indiana has both advantages and disadvantages. The typical pole barn built in these areas would not meet code requirement in most more populated areas. Most building codes require the builder to put a concrete pad under the base of the posts while the rural builders generally just dump a bag of concrete mix into the bottom of the hole. Most rural builders just nail (or spike) the girders and/or trusses to the posts while building codes may require the use of stronger fasteners.
I've had floor drains in two garages that I have owned, and am not a great fan of them. It seems easier to just slope the floor toward the garage doors rather than try and create multiple slopes toward several different drains. A floor drain sounds like a good idea if you want to wash vehicles inside in the winter, but it's hard to do that in a tight space without hosing down everything in the garage.
Garage floor sweating is a tricky issue. Moist air will condense on cold items, and the garage floor is likely to be cold. Plastic vapor barrier is cheap, but I often wonder how effective it actually is. If relatively thin plastic is laid down over a gravel base, will the plastic be punctured and torn when the slab is being poured? My pole barn was build in a low area, so I filled the area with a foot or so of crushed stone and have very good drainage now. I don't have a vapor barrier, and don't notice any sweating.
If you are going to eventually finish your building, you need to plan for it now. Most economy pole building will have trusses about 8' on center. The trusses may not be designed to support a ceiling (and insulation), and it is difficult to install a ceiling with this truss spacing. Truss spacing of 4' won't add much to the cost and will make ceiling installation much easier. Truss spacing of 2' will make ceiling installation even easier, but will raise the price.
I like the looks of a modest overhang all around, but it adds to the cost. I don't know the purpose of your proposed 6' overhang in the front, but it won't be cheap. Unless you have a specific reason for wanting such a large overhang, it might be more cost effective to just add 6' to the depth of your building.
The major cost savings of a pole building (over conventional stud construction) is that you don't require a foundation. The downside is that the poles will eventually rot. As a compromise, I used Perma-Column's.
https://permacolumn.com/
The added cost was about $100 per post (eight years ago).
One disadvantage of not having a foundation is that critters like to burrow under slabs. Some locations (with building codes) require a rat wall even when there isn't a foundation.
