I think the reusable cups/containers is a great idea, especially since people already accept the idea (grocery bags, water bottles, etc.). I also like the concept of hybrid planes, even though fully-electric aircraft are probably a long way away.

As far as the in-flight presentation, good luck. From my flying experience, most people don't even pay attention to the safety video.

Yes, that's a good idea. That way the app could be an option, but not necessary to see how much you would save.

Sounds good. The cost is lower than I imagined, and it doesn't seem like weight would be too much of a problem. As far as branding goes, foreign travelers are are probably the predominant customer for taxis, so anything that gets their attention would work- maybe even as simple as, "This Tuk Tuk Runs on Vegetable Oil." That way they'll want to take a picture, ride, and tip nicely.