Staircase & Bannister Staining and Sealing

We've just finished prepping our staircase & bannister (red oak) and are ready for staining. The only color (Mission Oak) we like only comes in Varathane's "PolyShade" which is a stain & polyurethane in one. We're hesitant to use it on stairs since reading on-line that it shouldn't be used on traffic areas such as floors or stairs. Your thoughts/opinion? Also, we want to put on a couple of coates of Polyurethane to prevent any wear signs the stairs. 1.) would it be okay to apply another coat of Polyurethane the the already has "Polyshade"? and 2.) is therea Polyurethane made for floors/stairs or can regular Polyurethane do the job without peeling? Any help you can send our way would be greatly appreciated