Easiest way for going over maximum is to just not upgrade the speedometer. Otherwise, you're going to need the get on a Cruiser and mash the hell out of the buttons. I mash both the mouse and the spacebar.
The Deploy button should show at the middle of the toolbar, not in the middle of the battlescreen. It's annoying to have to scroll back to deploy the line when I want to keep my eye on the base. The spawning option should be separate for infantry and vehicles. I prefer my infantry scattered, but I want to control where my artillery line up.
Am I the only one who uses Rail Gun? Well, anyway, for Level 29, use Rail Gun, Big Lazer, and Energy Homers. Go to the side and unload your Rail Gun and Big Lazer down a line. Then move away and use Energy Homers while recharging. Dodging is easier once a side is clear.