Negative on the fauna. Any puffer, yes, even a dwarf puffer, will gladly devour your RCS. Decision time, which matters more to you?
Dwarf baby tears, AKA HC, is hard to keep alive without "real" CO2 but is possible with DIY CO2. You will likely need to supplement with something like excel/gluteraldehyde.
Depending on your home's temperature in winter you may be able to cut the heater.
I would say that the ~$30 extra for the ADA would be a wise investment (which could be saved by cutting the heater out of the question) as it is aesthetically superior, in my opinion by far, and will hold a much higher resale value if something happens and you decide to sell it.
Frogbit will shade your plants and will only make it harder to grow HC in your tank (especially without any CO2). I'd say cut it. It can be an eyesore, anyway.
You haven't mentioned lighting? That's important. If you're asking us what kind of lighting to use, I'd suggest perhaps a 27W PCL by Archaea (which you could get at the same time as the ADA tank if you get it instead of the Truaqua) or even a desklamp with a spiral CFL bulb.
As far as a filter it depends what you're looking for. I'd suggest a ZooMed 501 or similar (e.g. Tom Rapids Canister).
Overall you've got a good basis and plan, but it will need a little tweaking to yield successful results -- and this is a results-driven hobby. Best of luck!
"Simplicity is the ultimate sophistication." -- Steve Jobs