All good advice, but please be aware that some macro algae like caulerpa will eventually go sexual...Ive only had this happen to me 2 times in 11 years and I've noticed that regularly trimming excessive growth will prevent the caulerpa from going sexual.
If you do decide to get macro algae just get some chaeto, that way you don't have to worry about it going sexual or getting into the main display tank and proliferating like crazy.
Also, since you are having an algae problem, I really don't think you should be feeding the fish (tang included) multiple times a day. For now, I would cut back to no more than 3x per week, at least until you get a handle on all the information and be able to implement what you think is best.
This must be very overwhelming for you but be patient and look for common themes among all the answers; aside from some of the unintentional misinformation I think you have a good amount of facts that should really help you in the process of getting your tank well on its way.
And if you see or read something you are confused about or feel mislead in any way, just continue to read; not just the forums but utilize other online resources like the ones mentioned in this thread and many more.
Check out
http://www.wetwebmedia.com/marine/index.htm for many hours of educational and beneficial reading.