This isn't a Jinbe flashback obviously. It's like that really exciting flashback about Tom we had.
Despite the strange pacing of the first chapter, jinbei pretty much tells us what the flashback will be about on the last panel before the flashback in chap 620. I think that those questions will be awnsered with otohime and tiger. However, the second half of the flashback will probably be about jinbei "releasing" arlong on the east blue. That, or he will tell us outside of a flashback.
lol, why on earth would he tell us outside the flashback? Doesn't that completely defeat the purpose of a flashback set up to answer that question?