I did that (well, Cambodia) at the beginning of 2010 ago with DSLR and RZ67. Used a bunch of slow, fine film in both B&W and colour (Pan-F, Acros, Velvia, Provia). That time of year, the light will be pretty flat because they're constantly burning things, so you won't get a golden hour at either end of the day; it goes dark -> grey -> full sun and vice-versa.
Film and processing was not available at all anywhere I went.
While in Siem Reap, make sure you get out to Beng Mealea, preferably at dawn, since it has basically no tourists compared to the other temples. We went there on a tuktuk (breakfast in the pre-dawn smoke while riding!) and were the ONLY tourists there for the first half-hour or so, in contrast to being in a crowd of about 10,000 waiting for sunrise over Angkor Wat.