Well, to answer all of your question.. I did not include bolts/nuts for this design although I have done that before and it is indeed a pain in the butt! Umm, To make tubular rails you need to draw the line you want the rail to be on, and then make it into a solid>cylinder. It's easy to do once you figure it out, but its hard to get it working initially. If you want to make curved 3D Tubular rails, you'll need to do a Revolve. That get's really complicated, that's how i did the ends on the rail.
Autocad is awesome but it takes awhile to get good and efficient with it. In high school we had 4 years of autocad, 3 years Acad and 1 year Architectural. So, i've been working 180 days a year for 3 years on Autocad stuff. It's pretty nuts.