Yes. If you keep up with small weekly water changes (about 25% of the tank's volume), then you should be quite alright. Having a planted tank helps filter out some of the toxins produced by fish waste so that helps. I'm also assuming you have the minimum acceptable filter capacity.
20 guppies in 8 gallon.
Its not recommended to do that, but guppies are very hardy fish. So if you were to make sure not to over feed, and to clean the tank frequently, then yes you could keep 6 guppies in a 3 gallon tank.
Guppies are surface fish and they also enjoy swimming/playing in water currents that is why they are there.
The answer depends on the number of guppies. A few guppies can live in a 2.5 gallon tank or larger, temperature between 72 and 80 degrees Fahrenheit. Many people raise fancy guppies in 5.5 and 10 gallon tanks.
no
4,000
yes they can, depending on how many guppies you plan on getting.
It depends on how many guppies, and how well you keep up the tank. In a ten gallon tank, I'd say no more than ten guppies, and do frequent water changes. 10-15% weekly. They need a filter and a heater, as well.
People most commonly suggest 6 guppies, but with the oversized filter in the fluval edge, you might be able to get away with 8. Just try to keep 2 females for each male if you decide to try to breed them.
No
NO! you will need at least 5 gallon for those
I would suggest upgrading to a 10 gallon tank.