I have an areo cloner but not full grow units.

Not sure about the pump maybe some one will help with that.

1- Sounds goodwith the rockwool. Sometimes I do the paper towel thing and then carefully put them in a small rockwool cube and into the hydroton as soon as roots show.

2- If I get this right you have a 3 foot by 3 foot area. A 400 watt would do it but 600 would be better. Me I would get a 1000 just in case I wanted to expand. In a small space the trick is keeping it cool with a hood or cooltube. OK, read it again and you want 2 area's. I would go with the 600's. 4's would do but you will be happier with the 600.

3-If your using buckets, Why areo ? You could just use an airstone in each bucket with one air pump and go DWC. Much easier.

4- For 2 flowering plants a 3x3 would work but give yourself a little room and go 4x4 at least if you can. If not it will work.

5- Yeild is subjective. What you are hoping for is 0.5 grams per watt of light. 600 watts would be 300 grams if no problems exist.. I have not grown white widow yet and look forward to it. From what I have seen it should be a good producer.

Hope this helps.