water does not effect metabolism. Eating right does. if you want to increase your metabolic rate, get your ass in the gym and start eating 5 small meals a day to keep your metabolism at a constant rate.
you do need a lot of water, especially if you're working out. But, you dont need to drink until your piss is clear, that just means you're drinking enough water to make you piss a lot.
dont taper off your water intake on rest days, rest days are more important than lift days....keep your muscles hydrated, or you're gonna overtrain and you wont get sh!t for results