As far as the entrance and exit, I was toying with two different options. Number one would be cuting a hole in the celing of the grow area, then droping a latter down, and entering and exiting from the attic. This isn't my main choice, as it seems like more work than is necisary.
My second choice, and probably the one I will go with is as thus: When I construct the 8'x2' wall, I will do it in two sectons. One 8'x1' section will be actual wall, and the other will look like a wall on the outside, have internal hinges and 'Tot lock' magnetic safty locks on the inside, and will swing outward like a door. The only concern would be the one long crease that would run down the middle of the wall. I havn't really thought how I would fix this problem though.
If anyone had a better idea as to the entrance and exit I would love to hear other options.
And I agree about the construction. If I could get it up in one day, that would be fantastic, and much less suspicious, but I'm giving myself 2-3 weeks for planning and in case something gets messed up. I already have to repaint my room, so I can do that after the construction to cover up any traces on the walls.

The benefit would be having a sealed off grow area. I have a cab right now, and have had two others in the past. I like them, and I planned on keeping my mothers in the one I have, but the space is just too cramped. I would really prefer to have a room, but don't have one that I can seal off to grow in. I am also too paranoid to just grow in one room of the house and 'lock the door'. I would prefer the added protection of not knowing that the grow room actually existed.