+1 on tuning the bike before you leave. Replace worn parts or parts that will likely become worn earlier in your tour and then make sure everything is good to go about a month in advance (or less if you ride a ton) and re-tune as needed before you leave. Don't be afraid to re-grease and retighten everything and make sure things have time to settle and wear in a little.

Either pedal system would probably be fine though you might likely find SPD or SPD compatible stuff in more places but then again if you are in rural Czechistan or some place like that you might not find any bike parts or very few. That is why making sure everything is good to go before hand and replacing stuff that is worn or will be worn early into the tour makes good sense.

Certainly if I was world touring or touring in less populated areas I would want a single sided clipless pedal with a platform on the other side just in case.