well i bought a bicycle on ebay.

+1 on the Time's-Crank Bros kinda knocked off on their design and made it 4 sided but for out west, i think the SPD's will be fine with a bit of lube now and then.
I prefer a smaller frame (5'11/32' inseam and my Ritchey is a 56) so i would be comfortable on it but there are a few cm's of +/-. The only person who can say if a bike fits is YOU. If you think it is natural feeling, go with it. Unless you are doing road TT, it really doesnt matter. as for bars, get your local shop to order you some cross specific drop bars in at least a 44cm width. Cross bars are going to have more width on top, a less aggressive bend in the drops, more cable routing options, probobly better shock absorbsion and fatigue life. I had Ritchey biomax bars on mine and the upsweep was very controllable on the rougher trails.
I would stay away from flats of any type of bullhorn or bar-end bars. Long story short, they will make your nice cross bike into a high end hybrid and the guys at your local shop will call you a person of other sexual prefferance...i was one of those guys, and i did Seriously, dont do it, it is like harley style drag bars on our R6's. If you dont wanna do traditional drop bars, do some old-school Tomac style bars (the ones he ran in the woods back in the early days) check these out, this is the design i am talking about only with more flat on top Soma Major Taylor Track Bars

As for wheels, the wheels on there are pretty high-end and if you are going to commute, trail ride, or otherwise beat on it, i'd get some tried and true traditional wheels. I have ridden and worked on all sorts of wheels, and i wholeheartedly and confidentally reccomend Mavic rims (straightest/roundest from the factory and nicely machined brake track) with Shimano hubs (does this need explination?), DT swiss spokes (14/15 or 15/16 double butted) with brass nipples, and Fond De Jaunt rim tape laced in a 3X pattern in back and 2X up front. Rims- Mavic Open Pro or Open Sport (pro's are light, sports are strong and will stay true longer, i'd go with the sports for cross) Hubs- Shimano 105 (cheap, Uber-reliable, and not too heavy). this will give you a very reliable/strong wheelset for a decent price.
The cassette thing is just a reccomendation, it will make wheel changes a 1 min affair instead of having to use a chainwhip and a cassette tool on a workbench to switch them out every time you go from slicks to knobbies. It will also give you the option of having a set of tall gears for the street and a more "aggressive" set for the knobbies. I would also HIGHLY reccomend a SRAM chain and at least a 105 cassette (also FYI, shimano cogs/chainrings may not be the prettiest, but damn they shift well)
Tires-if you know this, my bad, just trying to help.
SEW UPs- Think about a airtight cloth tube (like the one inside your tire) with rubber bonded to one side. Advantages-Less rotating weight, impossible to get a pinch flat (almost) whick allows you to run less pressure (within reason) hence better traction and most folks swear by their ride quality Disadvantages-PITA to install sometimes, VERY hard to change in the middle of nowhere, more expensive, rims arent compadible with clinchers
CLINGHERS (reg tires)- uses a tire and a tube seperately with tire held on by a bead, like a car tire. Advantages-any wal-mart probobly has a tube that will at least get you home, tires are available everywhere and are cheaper, easy to put on/patch, etc. Disadvantages- hard to run low pressures because of wandering feeling and pinch flats, rims arent compadible with sew ups, more rotating weight.
Paul levers are top-notch, their machining is damn near perfect but they're about $100. Tektro makes a product that is 75% as good for 50% of the price...just less bling
i know that was long, but i promise you, it'll be as clear as day once you get familiar with it. bottom line, forget all the CNC garbage and get what works for you, what is reliable and what you feel comfortable with. I hope this hepled and feel free to ask any Qs you have