Won't harm your plants and they get the food they want, 1500 should literally wipe out your problem, unless you are in a huge area of some sort, the more closed in the better.
http://www.horticulturesource.com/lady-bugs-1500-per-container-p3857/?osCsid=5ea15e2ddace94b0b2df82d4b692b5ae
Yes, more light equates to more penetration, hence the reason using CFL throughout the entire grow usually results in "Popcorn" style bud. If you read through some of the growers (Me included) that are budget growers they most ultimately suffer the same fate. Perfect for starting and maybe half...
The short answer is yes. You never have too much light. I would use the T5's as supplement light either in the corners or the sides etc. As long as it does not interfere with other lighting and you can get them close to the plants.
If I run into res temp troubles again I'm thinking of peltier cooling on a thermostat. I have some old water cooling puter gear new still in the boxes I can use to cool the water instead of the other way around. See how it works out.