You will need to remove the cassette if a drive-side spoke breaks. The NBT tool is precisely for this purpose.

One of the big benefits of bicycle touring is that it's cheap, especially if you come from motorbike touring. Keeping the machine in good order is much simpler too. A check every few weeks will let you know when things are about to wear out. Depending on how much you travel, replacing everything before you go, each time, will be a waste of money (you could always send me your second hand parts! ).

I replaced the chain/cassette/chainrings/rear-derailleur on my LHT after about 12,000 miles (and they were put on that bike second hand). I did it as a job lot, and it was about £80 (I think). Having said that, I went through 2 rear wheels and a front wheel in the same time (I tend to tour in bad weather, and up and down mountains, which chews rims/rim-brakes).

The terminal failures are (generally) frame breaking, or hubs/rims breaking. Breakages with things like spokes, chains, cables, bolts can all be fixed at the road side (assuming the right tools are on board). You can drop down to a single front chain-ring or single rear sprocket (if your derailleur/shifter packs up), for example. Everything else generally wears out very slowly, and you can see/feel it happening with enough time to do another 1000 miles.

I also agree about the uselessness of multi-tools. A proper set of L-shaped allen keys with ball-ends will make life much easier, for the same weight.

cheers,