I would rehome them all and get a betta and maybe some shrimp, you could get small tetras but in my opinion anything less then 10gallons is to small for anything but a betta.
Just let her do her thing. Not much you can really do to induce pregnancy, sometimes they will hold fry longer if something is wrong with the water. Maybe do a water change but other than that just give her time.
I dont know much about frogs but the fish list seems great! Glad your getting some bloodfin tetras I have a school in my 30 gallon and I love them! Good luck with the tank
I would keep tetras and corys in as high groups as possible. If you want the gourami I would do a dwarf powder blue female or another option could be an angelfish
A bit off topic but those tetras you keep in there with groups of two are shoaling fish and should ideally be in groups of 6+. Too often people say "they are alive so they must be fine" but truly they are stressed. I would recommend filling in your shoals.
You could call your LFS and see if they will take them. You could also check your local fish club or ask on facebook/craiglist. That is how I would go about it anyways.
Tissue cultured would be like the 1 2 grow by tropica. Basically you will get it out of water and plant it in the water. They grow quite quickly and are easy to maintain. I use fertilizer in my planted tanks but you dont have to. If there is effect on the fish i have never heard of it/noticed it...
That would be a cory catfish or corydora. I agree the best thing you can do is a water change. What are the water parameters and is there other fish in the tank. It would also help to see the tail that has been "eaten".