Okay im using the same method for my particular grow now. So I'll try to answer bullet by bullet.
1. I would assume that you could...In fact it may work to your advantage. I put my seeds directly under my 400 watter and I had to hand it about 40 inches above the plants. I've since moved it down, but If I started off with CFL's I could have hung the lights alot lower. Although once they get acclimated to the HPS they fucking grow well...Like weeds...lol
2. Ummmm...Im thinking you could pull and OZ per plant...depending on your setup. If you aren't going to use CO2 make sure your designated area has some decent air circulation. Im looking to pull anywhere from 10-12 grams per plant.
3. You have to remember your plants are still going to start off in a vegative state. It also depends on what strain you're using. My plants vegged for about 14-16 days, and now they're starting to flower. I'm on day 22 now. With an expected 6-8 weeks of extended flowering. So you're still going to be looking at 8-10 weeks total. YOu have to remember you're not going to gain much time with this method. Edit: You will...but not as much as one would think.
4. My plants average about 10-12 inches now. Im expecting them to put on another 6 inches...maybe. So you should end up with plants under 2 feet.
5. With this method I wouldn't suggest pruning. Just let em grow. You want all the energy to be put into the buds. With them being so small any uneccesary stress could mess with them more than what you intended.
6.Be careful not to overwater or over nute them. You're not dealing with a 4 foot monster. You need to be very aware of feeding schedules. People have the tendency to smother there plants with love. With this method it could severely affect your yield.
Note...Im not an expert or anything...so Im sure you'll get different input from different people. This is what I do, and it seems to be working thus far.
Also check out this thread...it's alot of discussion on the subject in here.
https://www.rollitup.org/indoor-growing/19368-single-cola-plants.html
good luck man.