Braze-ons - Are there at least eyelets on the dropouts? If so clamp on bottle cages and "P" clamps for the racks will get you by.
Chainstays - This should work OK just make sure that you avoid heel strike issues when setting up racks and panniers.
Brakes - They should be fine. Be sure to use decent pads.
No Triple - I would add one unless you will only tour where it is pretty flat. A Sugino XD600 46-36-26 can be had for about $80.
Materials/Technologies - No worries.
Tires - I like 27x1-1/4" Continental Ultra Gatorskins if you will be mostly on pavement. Wider is OK if you can find them in a good tire.