I searched the forum, but nothing.

There were a number of van services with departures from Koh Chang to Siem Reap when I was there in October. I didn't get any details, unfortunately.

1. does van go all the way, or is there a transfer at the border to a Cambodian van or bus?

2. Any idea how much to charter a van or taxi to Siem Reap.

3. Which border crossing do they use?

I don't have all the details, but from what I've read, you need to perhaps go from KC to Trat or Aranya Pratet, change buses, go to the border, cross, then catch a bus on the other side. A bit of a pain. Not sure which border crossing would be best.

Unless you are in a tour group vehicle which goes all the way to the border, or perhaps even across. They not as many hassles.

I'll try to do some research and see what I come up with. I'd like to do this trip fairly soon also.

My experience of this trip (albeit a couple of years ago), and of a few others I've spoken to more recently...

Crossing was at Aranyapratet. The minibus stopped at the Thai side, and we were told to wait for a big bus on the Cambodian side - meanwhile local taxi's tried to persuade us that the bus was cancelled that day, and they could take us for $100 (bit much for one or 2, but more reasonable if shared /3 or 4). Anyway, eventually the bus arrived and picked up those waiting (but with no real headcount). The bus then stopped for ages at a "pals place" for overpriced food/drinks/etc, and by the time it arrived in SR it was a bit late to search for places to stay. I had somewhere prebooked (& overpriced), but the motorbike touts were still in full flow of "that place is closed - come with me to my brothers hotel".

If you don't have anything prebooked, it might be as well to take the taxi option and then have time to look around.

I know of others more recently who booked a full package to SR, including return travel, visa's, 2n hotel & HB meals, and 1 day pass to the temples with a local driver guide, for 9000 bt pp (for 2), and no hassles.