Heavier BBs don't change rof, only the velocity. And as you already know, heavier BBs will allow for better bush penetration. And wind will have less effect on heavier BBs.
I find you actually can get better range with heavy BBs than light ones. They hold their energy longer than light BBs, therefore can overcome air resistance that would slow and drop a lighter BB. For outdoors, I always use .28, and they give me better range than .2 or .25 in the same gun.
On your other points, it seems like you've got it right. Start with the gear, then borrow / rent a gun for a game to see if you like it. It's nice to see a noob actually doing some research and having a good startup plan rather than wanting to either be a sniper or looking for the best 400 fps gun right from the start.