Hydrofarm and Sunlight Supply Inc are great product catalogs to check out for parts and equipment. They are also great learning tools. In a 4 x 4 tent you will probably only want to use 4 buckets. Any more and you may not habe enough room to get in and get in and around. Keep the reservoir outside of the tent if possible to help with cooling (if you use one). You will need one good air pump or 4 average pumps. I use a water chiller because my house temp fluctuate. The water temp kept getting dangerously high. Try to keep your air pumps out of the tent too unless you are using an air conditioner. You end up pumping hot air into the water. High water temps can ruin your batch. Keep them between 68 - 72. I keep mine a little below at 65 just in case of swings. There are some really ph stable nutrients that might help you not have to ph constantly. I just started using the cutting edge line and I am shocked at how the ph stays constant with my 6 buckets and 40gallon res. I have only been using these a few weeks though.
Please let me know if I can answer any other questions you might have and definitely upload some pics as you get going even just your setup.
You can check out mine in some of my previous posts.
Good luck. Talk to you soon.