Leasing out a iPad Pro Questions

Thinking about Leasing a iPad Pro what’s the cheapest data plan I could get with it? I don’t plan on using any cellular data with it. Also on the website theirs a 10.5 inch and the 12” (Latest Model) does this identify the 10.5 as the first Pro model and the 12” as the latest second model? I thought the 10.5” model was one of the newer ones.