House clearing and flashlights
I've been through house clearing training (Tactical Defense Institute) and night-time use of flashlight. Two points.
First, I would not attempt clearing my own house, let alone one I was visiting, unless there were visitors at risk (normally only my wife and I are present). Going through a live-fire house shooting at bad-guy targets is one thing. Going through my own house risking getting shot by a bad guy is something else entirely. Assuming it's a night-time invasion, I'd stay in the bedroom, call 911, and shoot anyone who tries to get in. If it's during the day, I have guns located around the house. I'd get one, call 911, then let the bad guy come to me.
I think putting the flashlight on the gun is a very bad idea. It means you have to point the gun at whoever you're trying to ID. There are several techniques for holding a flashlight in one hand and your gun in the other. They're worth learning. At TDI we were taught to keep the flashlight off, then press the button and sweep it quickly around the room, let off the button, and MOVE. That way you get a glimpse of the room, but don't let the light become a target.
I have night lights in several rooms in the house. They give enough light that at night I can see fairly well, but I'm in the shadows. Give them a try.