Welcome to Tropical Fish Keeping forum. And thank you for the compliment.
I'll respond on the lighting issue. This is tricky. I have a 5-foot 115g and the store had a 5-foot fixture, dual T8, that takes two 4-foot tubes. For a 6-foot tank, I can think of three options.
First one depends upon the tank design. It will almost certainly have a cross-brace at the top in the middle; this may be wide enough for two 3-foot dual-tube T8 fixtures.
If you are good at woodworking, you could build a tank hood incorporating the fixtures and use shop light fixtures,
Third option is T5 HO single tube, if you can find it. I would not use dual-tube T5 HO, I tried this in the 4-foot tubes over my 5-foot tank and it was too bright. I don't know how they make these, I think tubes max out at 4-feet, so presumably this would be a similar two- or three-tube affair. As you say, it will be expensive, and the T5 tubes are considerably more expensive than T8 so long-term there is added cost.
I would think the first option is probably the best. A glass cover sits down inside the lip around the frame, with the fixtures up on the frame. Just depends upon the design of the cross-brace.