You'll need to do a lot of traffic analysis to make a cost/benefit analysis of purchasing international capacity.

Transit is likely to be cheaper until you get big enough to hire someone to do this analysis for you. At that point, they will probably look at purchasing some small amount of transit from a larger ISP (e.g. Megaport, Verizon, etc) to allow you to peer freely with your largest sources of traffic. E.g. if you have a lot of Korean families who stream a lot from Korea, it might make sense to get a gig or two of bandwidth to Korea, and putting a router there to peer with Naver, etc. rather than paying for those 1 - 2 Gbps of transit. But it's probably not really going to make sense until you're in the 10's of Gbps.

Good questions. I know very little about international fiber markets, unfortunately. I do have a fair amount of experience deploying LTE in fixed wireless environments, though. I'll work on adding some of that to the site and feel free to reach out to me with questions.