I know it sucks, but lose the maxi pad and suck it up. Start doing shrugs and face pulls to help build up your upper back. Any type of pulls (deadlifts) will help with this as well.
Some people consistently line up the bar off to one side a little bit. In fact, I am sitting here thinking and it has been a long time since I have called somebody off the bar because they were out of line so badly I thought it was going to affect the set.
Bottom line, I have rarely seen it make much of a difference. If it is an inch or less, don't worry about it.
In regards to foot placement, you are over analyzing. I probably never set up with my feet perfectly in line and pointed at the same angle. Hell, I don't even look down when I walk out so I wouldn't even know. I do it entirely by feel.
More importantly, your body will shift and accomodate foot position. It really is not that big of a deal other than you may be a little crooked relative to the rack. So what? Unless you are off by several inches, you are fine.
If it really bothers you, put down two chalk lines on the floor, one for each foot, and work with this until you can put your feet within an inch or so on each side consistently.
Other than that, practice comes in the form of set after set, rep after rep. It really is that simple.