There are lots of ways to raise meaties, and everyone has their particular way they've found that works best...and most ways will work for anyone.
A standard way to raise is to feed a higher protein feed (20-22%) and then to start feed 12 hours on and 12 hours off at 5 days old, until processing time. This is a pretty standard commercial regiment. Welp has a guide of how much to feed for each week using this here:
http://www.welphatchery.com/cornish_rock_care.asp
Now, I personally haven't free ranged/tractored, however I do a free choice feed of a 21% nonmedicated grower feed from beginning to end, with no feed restrictions. I get the feed from my local mill (it's cheaper and more fresh). I bed deeply in fresh shavings and add shavings regularly to keep them from laying in their waste. LOTS of water is important - they drink much, much more than layers.
Experimenting is often done in this forum with meaties, and many have excellent results with different feeds, sprouted grains (there are a few threads on this right now), free ranging, and the like. To start, it's easiest to follow the same feed beginning to end, as long as it's nonmedicated (if medicated is warranted in your personal situation, then follow the withdrawal instructions on your feed), and choose if you wish to withhold feed or not. Just make sure they're housed as clean as they can be, and have lots of fresh water, and they are processed in a reasonable timeframe.