I have wondered for a while whether the time spent figuring out how to get paid for adventures is worth the income received from getting paid for adventures. Can I consider that question answered?
#1 Yes, the question is answered with $4.21--if DrivethruRPG/Lulu/etc. Maybe per month.
#2 Kickstarters--Higher numbers, but MORE time spent. If it's fun, it's totally worth it, but does bring on a heavy load of stress depending on your add-ons/stretch goals and how many people you are working with--might still end up the same as #1 once the dust settles despite large looking numbers, BUT-there is that value that you are working with commissioned art instead of stock art (or editors, or whatever). I think Kickstarters bring in a more polished product. Not sure how sales do after a KS, but can report it once I experience it. Also, some people nail it and seem to make a great profit (OSE, Glynn Seal, come to mind).
Reviews--Can boost sales if good, sometimes even if bad.
Learning point: For my own experience--Nevermore Mines. It received fair..leaning towards bad/verbose perhaps on Bryce's scale. I spent time improving it after the review and updated it. This ended up being wasted time as sales never really increased from the additional effort--which is too bad for that loss of incentive, but it was a good lesson on improving.
So yeah, writing adventures to make money, doesn't really work that well unless you go balls deep and go Kickstarters which is a whole different animal then just throwing something up on DrivethruRPG. But if its fun, may be worth it for the beer money. YMMV.