First Grow in the making

Hi, I'm going to be growing for the first time soon! I just thought i would post my whole plan and see if anyone has any suggestions. I plan to generally follow this guide YouTube - I Grow Chronic 1 of 9 (Marijuana hydroponic grow room setup) with a few minor alterations and some unfortunate twists. Instead of being in a basement it will be in an attic. The main problem with the attic is that it has two open windows and its about 50ft in between them (one on each side) so it gets really hot in the summer and cold in the winter. I was planning on using a fan and a duct to direct air out of the room and out one of the windows, and having a pivoting fan inside the room on a low setting as to not harm the plants but still have good circulation. Also, another problem, or might be problem, is that the ceiling is only about 6 ft high. Would 6 ft. be tall enough using the same set up as in the video? If you are thinking there might be a humidity problem, we have a dehumidifier we can put in the room and a humidifier in case it isn't humid enough. Tomorrow we are going to Home Depot to buy everything we need to complete the Vegetative room and start the Flowering room. Can anyone tell me what kind of mediums he uses and where you could find them. Also, where could i find drip nozzles like the ones in the video, and the nozzle hook ups. The only thing we will be missing in the Flowering room is an HPS light. I was wondering if you think I need a 400w light or more for 4-8 plants. We plan to grow 8 plants once we get the hang of it so i was wondering if i would need more than a 400w HPS for 8 plants. For our first grow we plan to grow White Widow just because we are greedy little bastards who want the goods and lots of it. I was also wondering how much you think we could yield per plant. Also, will smell be an issue to my friends room below, or the rest of the house, or neighborhood (remember the tube blowing air from the flowering room out a window.) Thanks for all and any help! (sorry for the repost admins)