Teresa, the biggest thing with a drum sander is keeping it moving. Be moving ahead with the sander as you gently lower it to the floor and slowly pick the sander up while still moving forward at the end of a pass. I would serriously consider trying to get a copy of The Family Handyman magazine, November 1999 issue, since it has a great article on refinishing floors. With 10 pages of words and pictures, it can tell you a lot more than I can here. You can order back issues for $4 each by calling 715-247-5060 from 8am-5pm, Central time, mon-fri.
I think that a spit coat on pine is well worth it. Pine will naturally have blotchy stain because of the way the tree grows and is cut. The spit coat evens out the pine's ability to absorb stain so you don't have the blotchyness. Since you will not need much to do a big floor, say a gallon of denatured alcohol and a pint of shellac, and there is almost no drying time, I think that it is well worth the little extra trouble. You can put it on with a big, wide foam brush. Just watch out for the flammability issues that I mentioned in the prior post and leave any rags that you use with this outside for a day or so.