Usually you should let him acclimate to his new home for at least a week before you consider feeding or handling.

Since you've already fed him, I'd give him a week of no handling now so that he can settle in.

Live vs f/t or prekilled - it's up to each individual keeper to decide what works best for them AND their snake. Mine all eat live each week like clockwork. None of them make your snake more or less aggressive.

Feed in the enclosure or a separate enclosure. Presumably you'll be in the enclosure for many other reasons besides feeding (tidying up, spot cleaning, freshening water, getting out to handle, etc). Your snake will learn that open enclosure doesn't necessarily mean feeding. However, if you go into the enclosure after you've handled rodents, and you give off a heat signature and you smell like a rodent - you're probably a rodent.

I feed all 40+ of mine in their enclosures each week. None of them expect me to feed them on any other day but feeding day. (Except the overachievers who are hoping the rodent goddess will bestow a rodent on them every time she opens their tub and would eat more often if I let them.)

I prefer to let my animals hunt from their hides, and many of mine would probably refuse food if they were moved into a separate enclosure with no hides for protection. I personally think it's less stressful to them to feed in their enclosure - they don't have to be moved twice, and once they are done eating, they just curl up in their hides and take a nice nap.

As for the S shape - get a water bottle and just lightly touch the top of the head and that usually will get them to duck their heads.