I would not try it
The tadpole may well make a meal of the guppy or at least bit chunks of the guppys fins. I would not advise it.
They can not go with there own kind but do well with guppies and larger fish...
a large one.
yes
Since that type of frog is a carnivore at eats almost everything it sees, I would say no.
No the beta will try to kill it
No.
to feed tadpoles you can either boil lettuce or spinage and put in inside of their tank
Silver Dollars are very large and boisterous fish (12 inches long) and need a very large tank. They may well nip the fins of a tiny Betta and make his life an absolute misery.
no
I have kept fancy gold fish that are around 2x-3x bigger then the beta fish in a 10 gallon tank. There are stories of fish being ripped apart. If you watch the tank after adding a beta you should be able to find out quickly. The less crowed the tank the better. Betas are very territorial of space.
No, you cannot put these two fish together. In general you should keep Beta's alone by themselves, not even with other Beta's. They are mostly kept in bowls without a light, a heater or an oxygen line. The Beta will kill your guppy.