This is a pretty great list! I agree; it should be stickied. I would just like to point out a few things. You recommend both endler's and feeder guppies in a 5 gal tank. Generally, it's better to try betta with tankmates in a 10 gal or larger. Even though these fish can be peaceful in the event of a squabble a 5 gal tank doesn't provide enough room to get away. My other problem is with the "gold gourami" recommendation. Gold gourami are actually a color morph of the blue gourami (
Trichopodus trichopterus), sometimes called three-spot gourami. These fish aren't recommended in anything under 36" (90cm) as they commonly grow to 5" (12.5cm) and would not be suitable for even a 20 gal long tank. I have also seen multiple sites recommend against keeping these with betta as they will grow large enough to see a betta as food.
Three-spot Gourami - Seriously Fish