Question for the Europeans -or others- that know the facts, only the facts ma'am....:

What happens when a US pilot shows up to fly in Europe, like Germany Austria and Switzerland for any number of months? Perhaps joining a club to help facilitate things.
Any preparation to be done here in the US beforehand? Medical required over there? Language barriers based on required reading/testing?.....
What lays ahead. I hope it's not a insanely massive paperwork chase like other stuff I've ground through over there.
Thanks