PHB II revises the teleportation language quite a bit to allow it to clarify how it interactions when you teleport another creature. However, it does not clarify these basic areas of uncertainty. It does calrify that YOU must have LoS to the destination space, neither you (nor the creature being telported) need LoE to the destination space, and the destination must be a space the creature can occupy without squeezing.
Teleportation is not forced movement, as that is defined as push, pull or slide movement in the PHB. Thus, rules relating to forced movement do not automatically apply. This includes the catching yourself rules on pg 286.
As far as I can tell, you can teleport a foe to any space the creature could occupy that is within range, to which you have LoS, and that the creature can occupy without squeezing. Throughout the rules, space is defined in 2 dimensions, rather than 3 (e.g.; On page 6 of the MM, the space occupied by creatures is listed as X by X instead of X by X by X.) As such, the rules really don't address issues related to having a third dimension present in the game.
I feel this is a gap in the rules that a DM needs to fill. In my game, I use the following rules:
* If you teleport a creature, you teleport it and everything it carrys or contains.
* When you teleport a creature to a space, it appears on the ground in that space *if* the ground is within X feet, where X is (5 feet times the range of the power). If the ground is farther away than that, the creature appears as close to the ground as possible within range. Liquid can be treated as ground or air at the discretion of the being using the power (you can teleport another to the surface of the water, or deep under water).
* If the teleport would result in the creature being in a space that would cause them to be submerged, or to directly take damage (as in from a fall or from appearing in a fire), the target gets a saving throw to negate the teleport (similar to the catching yourself rules on page 286).
Without these types of limitations, teleportation becomes one of the nastiest effects in 4E, allowing a player to instantly kill enemies in the right terrain or right situation. That is not in the spirit of 4E.