hey deryck,
a 150mm lens is a good starter lens, as it is similar in field of view(FOV) to the 'standard' 50mm in 35mm format.
FYI: 35mm focal length x3 = equivalent focal length in 4x5 format 85mm(35mm)=240/250mm(4x5)
Intended usage: B/W, Color or both?
4x5 film holders are really cheap right now, with many listed on fleabay, craigslist, etc.... I got most of mine for $5-$8 each. fidelity elites are really nice. lisco regal's are nice as well. start out with 5 or so, so you can load a full 10 sht box of film, if you shoot color. I don't know of any b/w that comes in 10sht boxes
darkcloth, or focusing hood(tube). cambo made one, and its handy. make sure your bellows are light tight though before you use the camera. ebay again for these...
loupe. a $5 one from longs should work for starters, or a pair of 3x reading glasses from the 99c store work too. and if you lose either, then you don't have to worry about it that much. backups are helpful to have in this regard, IMO.
-Dan