I have to question the idea of cheap brakes on a bike with a Chris King headset... Brakes are very geometry specific, if one is talking about cantis. So best thing is to look at the brakes the OEM puts on the complete bike, then either use those, or check around for a brake with identical geometry but better quality or results.

I wouldn't save weight on a folding spare in the wrong size. You could end up riding half your tour on that thing.

I wouldn't use those bars, get something wider for touring, and why have a bar that is specialized for brakes you aren't using. Spend some time at touring sites like Rivbike.

A lot of people do like san marco. Don't know that model, but just remember touring is totally different from racing as far as the time spent in the saddle, and the posture.

Get a square end Phil BB and you can ride your route 3 times before it needs service. Get a good triple like the Sugino. Square end is preferred in some non-shimano dependant circles. It may be easier to find in the third world.

Guns are a good thing, but you won`t realistically be allowed to carry one either at all in most SA countries, or without a mountain of paperwork in the US and Canada. Handguns are not great for the griz and polar bear sized stuff, but they have been used for stops over an over. More than enough for blacks. Way better than bare hands. But mostly only the US lets people carry them, and some of the stickiest places like cali are on your route. Your chance of getting a carry permit is really low. That said, get some bear spray, and don`t worry about it. Actually bear spray can be a problem at international borders. I live on property with black bears, in a province with lots of black bears, never seen one. Out west in the mountains I have seen them. I`m kinda divided on the issue. Being able to protect yourself would be a good thing. The need to protect yourself is extremely remote in most area. I wouldn't worry.