I have a planted Eclipse Corner 5 and have never had a problem with it warming up, In fact I have to add a heater. That may be because my room temperature is lower than yours as I live in Vancouver, BC. My Eclipse came with a 15 W incandescent bulb and I switched it for a 7 Watt compact flourescent. My plants are growing very well. If your tank gets warm, before you drill more holes in the lid, why not try propping the lid open a quarter inch or so to see if that helps? If it doesn't help, switch your bulb.
I did try a 10 W Coralife 50/50 in my tank for awhile but didn't like it because it had a very blue, cold look. I don't think my plants liked it either but nothing died. Coralife makes an almost identical one for freshwater planted tanks that you could try. But the one I have is from the drugstore, 6400k, and it only cost $3.
I don't think that you will have to put very much Excel into that tank (I put it into my other tanks but not this one) and the filtration and aeration should be fine.
Can you post pictures once you have them? I look forward to seeing your tank!
Here's a pic of my 5 gallon Eclipse betta tank.