Suggestions for my Hypothetical 10 or 12 Gallon.

Serpae are very nippy, I'd go with a less aggressive shoaler, such as rummy nose or black neon tetras, or harlequin/scissortail rasboras. It also looks better when you have one larger group of fish as opposed to several smaller groups, so go for 6 of one of those types (there are others, thats definitely not an exhaustive list).

As for ADF's I've never kept them, but they seem to be popular betta companions. You may want to add a few cories (one of the smaller types such as pandas or pygmies) as a cleanup crew.

HTH
Ryan

Here is a really good article on the ADF
http://www.aquariacentral.com/forums/showthread.php?t=37172
As for the tank, a betta and a frog along with the other 4 fish would be a bit overstocked, plus as slash said the serpaes can be a bit nippy and may go after the betta. What about the betta and the frog and a few pygmy corys (or even regular ones really)? Or a betta and snail and a couple of ADF's?

The tetras (both serpae and black phantom) are schoolers, and really won't be happy in a group of only two. Minimum would be three, but six or more is best, and then your tank is full. THe tetras will be much more nippy without a lot of them... I would do the betta and the frog, and maybe a school of smaller, more peaceful shoalers. Perhaps white clouds or cherry barbs. You could have five of them, with the betta and frog and as long as you kept up with tank maintenance (water changes etc.) would probably do o.k. If you aren't doing a fishless cycle, I"d add three white clouds to start, then in a couple of weeks (depending on what the water tested at) add another two white clouds. Then a couple weeks later, add ether the betta or frog, and a few weeks after that add the frog or betta (whichever you didn't add the time before).

Emily