Bettas should be kept at around 75F to 78F.
No, you need a 10 gallon aquarium. Bettas should not be kept in bowls at all. 2.5 gallons is the minimum.
Bettas are agressive towards smaller fish, so neither.
No. The tank is not large enough to house two female bettas. The basic fish keeping rule is "1 inch of fish needs 1 Gallon of water". A female Betta grows to around 1.5 inches so you would need at least a 3 gallon tank to house the 2 Bettas properly.
The bigger the better-- despite popular belief, bettas do not prefer or thrive in small amounts of water! Bettas should never be kept in less than one gallon, but the ideal tank is at least five gallons large.
If you attempt to breed Bettas splendens in a 1 gallon tank you are doomed to fail. Sorry. The minimum sized tank to breed Bettas in successfully is around 10 gallons.
This is a BIG NO NO!! Bettas need at least 2.5 gallons of water to themselves, and if you put a male and a female together, it will most likely result with you have two dead bettas. Keep your boy and girl in separate 2.5 gallon heated tanks.
That would be a standard 29 gallon aquarium
Fish are usually most comfortable when you house them one fish per gallon. Female bettas, unlike the males, don't really have any restrictions on how many individuals you have as long as you adhere to the one per gallon philosophy.
In most cases, it is not recommended to keep guppies with female bettas. Female bettas can be quite territorial and may perceive the guppies as intruders. This could lead to aggression and potential harm to the guppies. It's generally best to house guppies with other peaceful, non-aggressive fish species.
10 gallon tank.
You can put one maybe 2 one-inch fishes in your one gallon aquarium
Bettas and other Anabantids like old water. I would be replacing only around half a gallon (4 pints) of its water weekly.