These are great questions. Way to not be a yes man. Its great to think, learn and grow.
From what I've read so far in this thread is that based off your current diet the Carbs are high for YOU. With the information given they have come up with the idea that your phenotype is that of an endomorph which I tend to agree with. What it looks like they were saying is based on your current diet the only real thing that you could change because your diet was relatively well put together is lowering the Carb intake and raising the HEALTHY fat intake.
Do a little bit of reading on Carb timing, insulin response etc. don't get defensive i'm just saying that there is always more learning to be done for everyone. I myself am an ectomorph (which is a hard gainer) and even I will put on some midsection flub if I go all out on Carbs, its all about how you respond to them personally buddy.
Figuring out something specific to you will take a while you're going to have to try out all different sorts of things.to find what works best for you personally. I wish I would have taken the time to do so when I was your age I would be quite a bit ahead right now. I have a book you might be interested in, pm me if so.
Also, if I remember correctly you're 21 stay away from binge alcohol nights and sugary drinks.