Fourthly: Your posture seems a bit off. From the looks of the side pictures it feels like you've got a (minor) case of lordosis:
Click to compare for yourself. Improving your posture will definitely improve how you look. Fixing lordosis is a case of:
- Strengthening your core: that's why I'm recommending Starting Strength, since it has a huge focus on the core by doing deadlifts and squats.
Instead of following the regular routine (increase weight every session) I'd like to add this though: Focus on form until your core is strong enough (shouldn't take _that_ long if you keep going to the gym), only then should you focus on doing heavier deadlifts/squats. If possible, try to get someone to monitor your lower back when you're doing these exercises.
- Doing stretches, main focus on your hip flexors.
Here's a little image to help:
http://i.imgur.com/FCMrtMD.jpg - As it says, don't do the 3 core exercises (right part) a day before going to the gym, but on the same day (right after your regular sets, or before going to bed) you're going to the gym. The stretches (left part) can/should be done daily for a couple of minutes.
- Actively monitoring your posture (least important part imo, but still)
It's hard to change your posture, since you've gotten used to it over the years. Some people recommend setting an alarm every x minutes, so you're reminded to sit correctly (sit upright, and tighten your butt and abs mainly).