I'll add a couple points. First, on load distribution ideally about 70% of the weight in the pack will be close to your back, and distributed vertically between the middle of your back and 2-4 inches over your shoulders. The rest of the space can be filled with high volume - low weight items such as insulation.
Secondly, I have gotten to the point that too many pockets is worse than too few. Have one large pocket with all your frequently used gear and you don't have to look through 6-7 pockets to see where you put something. I find it to be faster and easier.
Guy touched on food. I really prefer highly calorie dense foods on the trail, which usually means a high fat content. Also, for whatever reason, when backpacking I have little appetite even though I'm burning a lot of calories. Many people I talk to have experienced the same thing. To combat this, count the calories in your daily food bag and make sure you're getting enough to keep your energy levels up.