Forward oil creates the shape of the pattern, while the reverse fills it in and gives you the hold area that the pattern dictates. The ability to use both Fire and Ice is an added feature so the center can have some of the pattern transition more quickly (fire).
Having said that, I believe most will use Ice only for the THS and leagues because nowadays no one wants to move. They want to slide on ___ and aim at ___ the whole night.
Stone Street is 42 feet, and my best area to play on the fresh is straight up 7-8, and I mean straight. I can use nearly anything, but something with less polish is usually better while I'm warming up and getting used to how the ball is coming off my hand that night... Last time it was my Einstein at around 2000, maybe 3000.
Guys with more forward roll tend to find it more forgiving, but that's not my natural game.
My Tuesday league is second shift on Stone Street and my moves are much smaller as the night goes on. Hope this helps.