Kav- as far as film goes, I'd not take much 400 - unless you are planning to do a lot of night or indoor shooting, 100 is perfectly adequate for that part of the world. SE Asia is VERY bright. I found myself struggling to be able to get shallow enough depth of field at times when I wanted it, and I was shooting a 35mm SLR with a top shutter speed of 1/4000. Your Hassy is limited to 1/500th, and the Speed Graphic 1/300th with the in-lens shutter or 1/1000th with the focal plane shutter. If you are planning on doing lots of indoor/night shooting, make sure you have a tripod/monopod, and then you can use Tmax 100 for your b/w film, as it has the best reciprocity characteristics out there. After a point, with long exposures, it ends up being faster than most 400 speed films. I'd take Portra 160 as your color film, or if you prefer something a little punchier, Ektar 100 is BEAUTIFUL.
As to getting a WLF for the Hassy, go to the KEH website and buy one- they almost always have multiples in stock. I'd also look there and on Ebay for the AA/9volt adapter out there for the 500 EL/M/X series - It's a lot more convenient and you don't have to deal with the charger for it either.