He's adorable. That cage size should be fine. He'll just go up and down more often. Cooler is better than too hot. I would consider 85 the highest basking temp you need. He'll be happy with something more like 80.
Let it cool down at night. Unless you let your house get icy (so you have to wrap up to go to the bathroom at night) the regular house temperatures should be fine.
He looks pretty good to me in the picture. He's maybe a tad dark, but given how photos work, that might not be accurate. His eyes look good. Some Fischers are brown by nature.