Thanks for stopping by Smacko.
Good call on going the Supersoil route for your first grow, if you follow Subcool's instructions with the SS, you will grow A1 buds from the start. Even though I posted my recipe at some point in my thread, I would recommend using Subcool's recipe for your first run because I am not sure what I am doing
As far as light goes, there are a lot of good products, some pricier than others and some are poor quality and it can be difficult to chose the right brand for you. I have been very satisfied with my FERO lights and they also have lifetime warranty. Brent at FERO mentioned in an email to me that they will stop selling to end user, so that might be why you cannot see the prices on their website at the moment. AREA 51 has been working in partnership with FERO and they carry the same lights.
Personally, my goal is to grow big potent buds and I prefer to have more light per sq/ft than needed, so in your 4x4 room I would shoot for 800watts. If you are simply trying to have an economic/efficient grow (power wise) and being that the price per watt is more or less the same if you buy small or big units, I would strongly recommend putting the extra 100$ and get 4 x A51-90 as opposed to an AF-600, that is if you want 600W in the 4x4. It also depends on your budget I guess but if you plan to slowly upgrade your setup overtime, the AF-600 makes for an excellent main light source and eventually you can add side lighting.
Also 4 lights will give you much better coverage than 2 in a 4x4 squre, aso if you are not buying the AF-600 I think I would go with 4 smaller units.
If you have a good setup (24/7 fresh air in the room via carbon filter and inline fan) and a dehumidifier, you could grow as many as 9-12 plants in 7 gallons container, but it will depend on strain, I can tell you right now 4 Agent Orange in 10 gallons 12/12 from seed would fill my 4x5 space!!! So it really depends on the strain and only time and experience will tell you what to do, I am a beginner too keep that in mind!
Good luck and thanks for you comments
EDIT:
I should add, whether you have 1 or 4 lights, you will probably find that you dont need to move them. I dont move my lights I train my plants.
Regarding the size of the tent, more space is always better, it's a real pain to water my plants sometimes... its more about what is it that you want out of your grow, realistically, you should get at least 1oz per sq/ft on your first grow with SS, I got 12oz from my 3x3 tent on my last run and it seems to me like it will not be hard to do that again, and thats without veggin my plants too. So if you want 1 lbs every 3 months, you will need to stay on top of your shit and keep that 4x4 space loaded.