Yeh good stuff, sounds like your on the right track then. Maybe make the ES your market.
Faster execution will definately decrease slippage (though if you set stops, you should be fine on your exits even without the fastest execution, just may not be able to bank open profits as quick and may loose some of them), though it's hard to know the difference between the sim and live until you jump in and do it. But definately get a positive expectancy and know how you got it before you switch to the live market. A whole new array of things come into the scenario then (not just execution speed).
Obsessed? ha ha, I know that feeling! And a good one it is! Though I never seem to have dreams about it......only nightmares!
Good luck bud.