Hanging stuff on basement wall

I am preparing to frame out my basement. From reading archives and posts here, it appears that a 2"x4" wall with a pressure treated base held about an inch off the concrete wall is the most recommended. I have a tap-con set so would most likely use that to screw the treated boards to the floor. I have a few questions: How often should I screw (Tap-con) along the base? How tall should I make the wall? Do I figure it to fit tight against the upstairs floor joists? Do I figure this a little short and shim it where I nail it to the floor joists? I guesss I am worried about how hard it will be to stand the wall up if it is figured tight. I don't know if it is possible, but it seems like you could jack the joints up as you try to cram the wall in place if it is cut tight. How often do you nail at the top? Thanks in advanced!

in the planning stages of finishing my basement. one thing i would like to have is an open stairway leading down into the basement. by open i mean no walls, just railing on both sides. currently there is a wall on both sides of the stairway. both walls are drywalled on one side only (the side facing the stairs) so i can see the type of framing used. the top of one of the walls butts up against a steel beam. i am faily sure i can take down this wall w/o any problems. the other wall butts up against the floor joists. i am a little hesitant about this one, but i noticed that the wall does not have a double 2x4 at the top. is this the sign of a non-load bearing wall? thanks,