Enclosure Issues

[Zymurgy9]

I just have a few issues with my enclosure. I have had my almost 1 year old male veiled chameleon in this enclosure for about 3 months now. It is the XL ZooMed Reptibreeze (2x2x4 i believe). Lately my plant (schefflera arboricola) has been shedding a lot of leaves, and over the last couple of weeks i have found mushrooms growing in the soil. I pull them out at the bottom making sure i don't crush the cap and release more spores in the soil. The last S.A. plant I had died from over watering and i dont want to have to re-pot this one and have the same happen.
Another question I have; Is there a recommended wattage light i should use for a basking light. I currently have a ZooMed 75w heat lamp, but only brings the basking spot up to 97(low 80 to high 70 ambient), and from what i read the basking spot needs to be hotter.Yes? I also have a 60w household bulb just for more light and warmth in the top. Just don't want to get something that will maybe be too bright and hurt my chameleons eyes. He has also been very dark lately and not moving as much as he used to.
He got a little fired up when I got in his cage to take these pictures.

 

[Reptar88]

I'm having this problem as well(minus the mushrooms). I've pretty much narrowed it down to one thing insufficient drainage which has caused my plants roots to rot and I believe this is why the leaves keep dropping. So my only solution to offer is buy a new umbrella plant, re-pot it and drill tons of holes in the bottom so it can drain properly if the soil gets over saturated.