If any shop has a freeze ray, you can grab it, shoot the shopkeeper, and jump on him for an instant kill. With regular shops it's 100% guaranteed, 100% risk free. In the market, the biggest danger would be the next-door shopkeeper, but if you're fast enough you should be able to grab the shotgun of the just-shattered shopkeeper and blast the live one, especially if you killed the first as far away from the second as you can (the first one will follow you as soon as you grab the freeze ray, so positioning him is easy).
There should never be a damaging drop in the main path of a level, but you might have to hang from the edge before jumping down, and/or land on elevated blocks. In theory it should be possible to complete the game without using a single rope or taking fall damage. By the way, even though you can catch an edge while falling to completely negate fall damage, again, the game will never force to do this to avoid damage.
Also, to hang from an edge, do not crouch-walk towards it; doing so makes you drop your held item. Instead, walk off, then immediately hold the opposite direction as you fall. With some practice you can do this 100% of the time, even running.
Well aware that the freeze ray makes killing single, neutral shopkeepers easy. I was saying that it is not useful in a black market situation, or at least that there is no reason to do so when you can use the tactic I detailed in my post. Grabbing ledges is incredibly useful, especially on the Ice Caves, but as far as dealing with long drops in general when there are no ledges to grab onto or it's difficult (ledges don't line up), you can just learn how far you can fall without taking fall damage. Look down, and you can safely fall to the second block from the bottom (this means no jumping obviously, and if you hang from the ledge and drop you can get one more block).
Wait, if you freeze a shopkeeper, the fame won't set the aggro flag and other shopkeepers won't be mad? Am I reading that right?
No, shopkeepers will be aggroed as soon as you shoot the freeze ray.
Also, Spelunky's getting an update!
https://twitter.com/StoryFort/status/426851476062085120
The new Spelunky update contains a couple added features, but is mostly bug fixes. The biggest addition is a less intrusive HUD option.