The balance issue is one everyone who tries squatting real low suffers, that usually gets easier.
Increased stress on various parts of the posterial chain is normal as you haven't directly exercised these though this kind iof range before, you are a newbie again
The lower back has work a lot more to keep the back from rounding, than when you go to parallel.
If your getting a video try to get a view from the side filmed from about knee height, then from the front at about the same height (if you can get it from both that's better, but if only one, then the side is best).
Remember not just to take into account my views on squatting as others have just as valid methods that have worked for them. I think Ryan had some problems sorting out a squat that worked for him & Joni had to go real wide stance to get a squat that's comfortable. I'm sure there are others out there that have various methods of proforming squats that work for them too.
Final point remember its not the weight on the bar that matters to you, it's the intensity, if it's real tough going rock-bottom with an empty bar, for 10, then only adding 1Kg, so you can just make it again next week is fine that's still going to be a a good weight on your back if you keep it up for a few years, & that's what we're looking at, aim at long term squatting health, if you can keep squatting, adding weight when you can for a decade, how much do you think you'll be holding on your back
I've recently started a double progression system for squatting. I've been starting at 20 reps, then adding 2 reps a week until I get to 30 reps, add on 5K & start again. At the moment that's working for me, when it stops I'll change it, but it's a useful method for keeping you going up slowly.