The way I think of it, is if you have the camera pointing forwards (put the pan switch forward), then the green arrow points 'home'. Push the stick in that direction and the H comes back to you. It doesn't actually matter which way the camera points, but that makes the arrow make sense.
I thought the H's chunking was on file size, not time - sure I saw a longer film than 5 minutes, but that's probably wrong. I film everything in raw and run it through a pre-set set of filters to get the most out of it before sharing, so it doesn't hurt to join segments at the same time. It all rather depends what you want to use your film for though.