My parents did a lot of the building on their house themselves, I was 15/16 when they were doing it. We put down the wooden floors ourselves (or Dad laid them, I got the totally crappy job of punching the nails & puttying the holes).

If you think the nails will be high enough to hit the sander when you go over it, definitely get a punch and hammer them down. Then go over with putty. I found the easiest thing with the putty is to have a damp rag handy and wipe off the excess, instead of waiting for it to dry and sanding it.

Something to be wary of with the sander is the paint around the skirting boards - one of our rooms had been painted before the sander went through and it ruined the paint at the bottom. I don't know if that's just because there wasn't anything to protect the walls and there should have been, but the sander needs to get right up to the edge to make it all look even.

Then we got this special broom thingy. It had a wooden head that you put lambswool or something on, I don't really know sorry. Then we basically poured the polish on the floor and spread it along the grain in big sweeps with the broom thing. I have no idea how you do a stain, I think you have to kind of rub it on with a cloth?

That's all I can think of for now!