My wife has her heart set on Texas mesquite floors. At the price of this stuff, looks like I'll be doing the install to stay within budget. The flooring is solid mesquite milled 1/2" thick and is going on a 3/4" plywood subfloor. Should I use a traditional heavy duty stapler like the M111FS or one of the lighter ones that shoot 18ga staples (Senco, Spotnails, etc)? I'm worried about splitting since the stuff is so hard and comes in fairly short lengths.

This is going on the second floor of our house. First floor is on a concrete slab. I understand roofing felt is typically used as a vapor barrier. Since this is on the second floor with no moisture concerns, do I still need anything between the flooring and subfloor such as rosin paper?

It will bend 18 gauge staples. Use 15 gauge,1½" long