I don't see how freeze ray is even remotely useful here btw, hah.[/spoiler]
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).
How do people deal with the long drops on some jungle stages? I don't always have ropes, and last time I couldn't even see an enemy to land on. Am I just boned if I get myself into that situation?
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.