Questions about brazilian walnut and finish

I (hope, if he accepts my bid) am about to do a 5" wide plank brazilian walnut floor w/ a 10 year finish. All I have for a nailer is the bostich stapler and I was told not to use this but to use the cleat nailer because the brazilian walnut is so hard. Is this necessary? I could definately see the staples braking off the tongue like it does to hickory but have never worked w/ this type of wood and w/ hickory I have used my stapler. If so, has anyone ever used the grizzly cleat nailer (looks just like the bostich but 1/2 the price and it's green instead of yellow) and does it work well and does it use bostich cleat nails? I would hate to have to order grizzly nails every time I had to use it!
Also w/ the 10 year finish, the guy has 3 black labs and I'm affraid the finish isnt going to hold up so I'm concidering doing a light sand and topcoat w/ a polyurethane over the factory finish. I've never done this over factory finish and was curious if it was as easy as a light sand and put down more finish? I know that's alot of questions for one post but thanks for any help...