LTG said it best as to checking locally into licensing and insurance. But as far as free play goes, based on my experience as a volunteer tech where there are over a dozen routed machines and other locations where I play, I would make all machines coin drop but offer a variety of prices--anything from 50 cents to a buck--and people will pay and play. Customers (even kids) don't seem to mind paying, especially if they can get matches or free games--and if they have a variety of options they seem more likely to play, with the idea being that they see different games as offering "different deals." The 75 cent = 1 credit with the $2 = 3 credits option works really well for some. Ad maybe at least one game that offers 5-ball play is another way to enhance the variety of options. People honestly don't seem to mind paying a buck a game if it's a high-end machine and has a bill changer. And as others said, the cash box will tell the tale. I like the analogy of more roads taking you to the same place increases your travel options, and different people will choose different roads, with all of them being used.

Good luck!