Squat and bench are fine IMO, you know where your problems are, so... just gotta fix em is all.
Here is me deadlifting... http://www.youtube.com/watch?v=3gQv8lk3M04
As I watch the video, the bar seems to be going in a vertical path, which is what SS says it needs to be. I think my back position deteriorates further into the sets though. Oh, and notice the hawt rolled up sleeves, hehe. It's all the rage right now!
Alright, first off your belly isn't that bad. So relax, you'll take of that in no time, lol
Second you are basically standing up, and then lifting the weight. Your hips shoot way too soon. You feel deads in your lower back and lower traps (Mid back) a lot I would bet. That is because you are lifting the bar off teh ground.
Try and pull the bar up, if that makes sense. Push the earth down with your heels and pull the weight up. Don't lift it, pull it. (I understand that might not make any sense at all, lol, but I don't know how else to describe it.) You will lose a ton of power because you remove your glutes & legs from the lift too early. You shouldn't be squeezing your ass until you pass your knees. Once the bar passes your knees, THEN squeeze your glutes and it stands you right up, this is called "getting your hips through".
Now you are going to get some erector fatigue, obvi, but your ass and hammies should get sore too.
I feel like your back is in a decent position, it is just the bit of extra flab that makes it seem rounded. I have the same problem, so please know I'm not trying to knock you, but I carry my fat there as well.
Good news is, you are on the right track. You will be able to add weight as you work on form IMO, you will just make your back stronger.
Oh and drop the running shoes now. Dead bear foot because you are at home. Or pull in work boots, army boots, chucks, vans, wing tip Bostonian, or anything other than running shoes. Use teh running shoes for walking the dog, not lifting weights.
Good work so far man, good work.