Anyone know which quest form or script handles fast travel.

What do you mean?

Look at http://www.creationkit.com/FastTravel_-_Game if you want the player to fast-travel to a certain marker.

What determines locations you can fast travel to are Map Markers. If you place a Map Marker there checkbox under it's properties that allows fast travel to it.

There's also http://www.creationkit.com/EnableFastTravel_-_Game which enables/disables it game-wide.

One more thing - World Spaces has a property called "Can't Fast Travel From Here", I doubt it's used much though.

The script or quest that will make the player's horse fast travel with the player, even if the player is dismounted.

I guess this also handled pretty easy by making the horse a follower if you own it, which most likely is handled in the conversation with stable owners. If you pay attention to it in game you notice that only horses you own follow you on fast travels if you do not ride them while stolen horses run away (back to the place you got them) as soon as you dismount.

That's only a guess though. Haven't tried it.

There's a horselastridden property too (that isn't called horselastridden, but I'm close).

I tried a follow package, and yes it works, but it also allows horses, or whatever, to enter cities. They will even cross load doors into houses or caves (although IsInInterior will stop that). Vanilla player horses don't have a follow package, which tells me there's a better way. It will be similar to MoveTo player, but only when map markers are clicked in the map.