It isn't possible to give advice about sizes over the Internet, because without a deailed breakdown of your measurements and an understanding of what riding position feels most comfortable to you, we'd be guessing.

Wanting to assemble your own bike is laudable, and there are plenty oF "how to" videos on YouTube, but you don't need to do everything from scratch to be competent to ndertake running repairs on tour. You can't carry spares for everything, so if (worst case scenario) your bottom bracket goes, or you break your front forks, you're going to have to find a bike shop anyway. Focus on understanding how to adjust gears, trim a wheel if you bust a spoke or two, adjust your brakes and gears including replacing a cable, fix a flat and replace a link in a broken chain. That is as much as I would do by the roadside.

If you buy a decent steel frame it will already be painted and will have been treated internally to resist rust. And obviously corrosion isn't an issue with aluminium. So don't worry about the rain, bikes are meant to be ridden in the wet. Just make sure that whatever panniers you buy to carry your gear are waterproof. I like Vaude panniers, some people swear by Ortlieb, a decent bike shop will show you some. Blackburn make good racks, front and rear. Before buying any, have a look on e-bay, there are often bits and pieces there.

Your list excludes the most expensive components. Brakes, Derailleurs, shifters, chainrings and rear sprockets, cranks. These are the reason why it is often not much cheaper to go for self-assembly than to buy a complete bike - suppliers do much better deals on the component prices on a complete bike than you can expect when buying separately. So all things considered, in your position I'd identify the best bike shop within easy reach and go to talk to them about your requirements. For a start, they will be able to tell you what size to buy. They may sell used bikes, they may be able to source a reasonable tourer that is new for less than $1000. my advice on that isn't worth much, because I am used to UK prices, but over here I could get you a decent tourer for that money. And if you buy newand still want to learn how to fix it up, all you have to do is take it apart!