Sounds like a very awesome tank! For plants, you could try looking on Ebay perhaps for sellers who ship to your location!
Many people do not recommend having frogs with fish because frogs have very specific dietary needs/specifications, which vary greatly from the needs of a betta.
Depending on your betta’s personality (do you already have the betta?) it could do very well with shrimp and snails! A lot of people feel that because bettas are solitary by nature, they shouldn‘t be mixed with other species, such as tetras. Many people keep bettas with neon tetras and have great success and happy fish though, it really depends on the individual betta and if you are willing to risk it not working out. I would probably try to stick to just one schooling species in your tank size, with the betta, shrimp, and snails