Fast 'n' Free is just eBay's way of trying to force (scam) eBay sellers into offering free postage (which in turn just inflates the prices as everyone puts the postage in the item itself, but that means $$$$$ to eBay once people start charging postage again on the inflated prices) and a fast handling time e.g. same or next day postage. I did that on a couple of items and they showed up as Fast 'n' Free - offering Express Post (free or not) is not required for the (pointless) little stamp near your username. Offering "free" postage may (or may not) help your item stay below page 500 in Best Match, but given that Best Match is rigged anyway (due to the "lights on/off" rule and now the bribe-eBay-to-push-up-your-itmes Promoted Listings) it really doesn't make a difference.
