You dont need GPS to tour, just some good maps a compass and some navigation skills.
Good bike shops are plentiful so spares will not be a problem. As long as you can get to the next town you will be fine. Dont fret about forgetting stuff, you can always buy it along the way.
I carry a tyre boot (rather than spare tyre), 1 gear/1 brake cable, 2 spare inner tubes+ puncture kit, a spare sram chain power-link and a couple of spokes, although a fibrefix kevlar spoke is more useful. A selection of zip ties, duct-tape and string may come in handy.
Travelers cheques are of little use these days. Every town has a bank machine but I prefer to use the ones inside banks during opening hrs, in case it swallows my card.
Light, quick-drying, packable clothing is widely available. Jeans are the worst touring legwear ever. Be prepared for some cool mountain crossing. I would carry some ultralight waterproof pants just in case.