I really think most supplements are a waste of money, I'll probably get flamed hugely over that statement

. But over the years, I threw a fair amount of money into them too. Drink a ton of milk, skim. Good protein although a lot of natural sugar, but it won't matter to you at your age. Tuna and chicken are cheap and excellent sources of protein.
You point out that your older brother is much stronger than you. You don't tell us how old he is, so I will assume he is 16. There is a big difference between a 16 year old and a 13 (almost 14 year old). He is well into puberty, you are probably just getting started. Expect him to be bigger and stronger for a while, but you will catch up and potentially even pass him, once your body settles down.
You asked about military presses and bent over rows. Someone said it here, just google it. And as far as machines versus free weights, you'll notice a lot of opinion here on that! My thought has always been free weights are better.
How are the workouts going??