lenses for my 7D - please help!

[syder]

The 50L is a superb lens but its overkill for video. Its meant for high speed stills but you wont notice the difference in video. Get the 50mm 1.4 canon

+1
You really won't need the 50L, it's a great lens, sure. But that single step won't make difference. Also, if you would've ever tried to focus even with the 50mm f/1.4 USM at wide open aperture, you'd realize how insane f/1.2 would be. And for video even worse!
I would also consider the 50mm f/1.8, although it's made out of plastic, optically it's superb! Some do even say that the f/1.8 is superior to the f/1.4. I don't think so, but they're really close together in points of IQ and sharpness.

Focussing with the 50/f1.4 wide open is fine... Just get a z-finder/lcdvf so that you can see what you're doing.

Focussing with the 50/f1.8 wide open is horrible. The miniscule tensionless focus ring with minimal travel is a nightmare for accurate focus pulling. It really isn't an appropriate lens for video unless you absolutely cannot afford the 50/1.4

The 50/1.2 is nice, but overkill for your needs. The 1/2 stop is actually quite a big difference in extreme low light, but that isn't what you're doing.

As everyone else has said though, based on what you've suggested your usage is, a dedicated camcorder would be a better choice.

People haven't mentioned extras, which are a must for DSLR cinematography - Z-finder, variable ND filters, external mic, external sound recorder, some kind of support rig etc - with something like a sony Z7/panasonic HVX200 the only one of those you'd need to consider would be a shotgun mic (and even then the sound that comes with those cameras is miles ahead of what you get out of a dslr).