I have similar questions but I live in Europe. In Europe the requirements are varied by each member country. Some are easy and some extremely difficult. Here in Hungary there are pretty loose requirements for flying but they will change in 2018. Currently, you must be a licensed pilot to legally fly (although unless you are actually stopped which doesn't happen unless you do something bad, no one checks). I am a FAA licensed pilot SEL but way out of currency. I took the ALC-451 course but cannot apply it to the UAS license as I am out of currency and the FAA has removed all designated examiners out of Europe. So, I do not have the license yet for the UAS. I plan to take the test in May when I am in Las Vegas as a tourist so I will have that problem more or less solved and can then transfer that certification over to the EASE UAS license. The $155 test is a lot less expensive than the over 1,000 Euro course and test here in Europe.
I carry along with me my FAA license, my certificate of completion of the Part 107 course, operator's handbook, and a logbook which shows maintenance etc. and so far that has been enough. However, I don't attempt to break the laws.
Anyway, I was planning to take my DJI Phantom 4 with me to Austria in a few weeks but Austria has what I think are the strictest requirements yet. It is wildly complicated as only the Austrians or Swiss can do, but, basically if you take pictures at all it must be registered as an aircraft (250 Euros plus depends on processing time), you must have a UAS license, you must submit 3 photos also showing controller, an airworthiness certificate (the DJI manual is sufficient) and you also must have insurance coverage of at least 750,000 Euros t get registered and approved. Failure to do so results in a 12,000 Euro fine for EACH photograph. Once you get approved then you must comply with the more or less ordinary regulations which are similar everywhere now. Anything that goes over populated areas is automatically bumped up to higher requirements and of course additional approval and an additional 250 Euros. The costs are based on time required to process the application and any translations. I did find the Austrian Model Aircraft Club provides coverage but as far as I can tell is not worldwide. I decided it isn't worth the hassle and I don't have the months required to get approval so will not take my drone to Austria this trip.
I do a lot of travelling and it is a daunting prospect to try and get the drone registered for every country but that is apparently how it is going to be for a while. I am also travelling to Namibia in December and they have similar requirements of licensure and insurance although appear to be less restrictive on use (maybe). I am still in the process of getting approval through their civil aviation organization.
So, I am looking for the cheapest worldwide coverage that covers even insane requirements like Austria. The AMA membership seems the way to go for me but I cannot tell if they provide coverage outside the US. Here in Europe ordinary insurance is only available for commercial usage. I do not plan to do any commercial work at all.