Wikipedia has a good list, its not complete, but its good.
A lot. The Greeks worship many gods and goddesses so you can't find the exact number. There are many major and minor Greek gods and goddesses. You have to be more specific, how many Greek major gods or how many minor gods.
athenaartemisapollodemeterherahestiazeusposeidonhadesdionysuspannikemorpheushecatehypnosboreaszephyrosaeolusnotoshermesjanusjanuamphitriteaphroditeerosareshephaestusmercuryplutopomponatritonminervavenusneptunevulcanhebepersephoneproserpinaheliosdelphineus
both
No not all Greek God's live on Mount Olympus. There are minor gods like Hestia and Janus. They do not live on Mount Olympus, only the major 12 do.
Janus is a Roman god, and not minor to the minds of ancient Romans.
A lot. The Greeks worship many gods and goddesses so you can't find the exact number. There are many major and minor Greek gods and goddesses. You have to be more specific, how many Greek major gods or how many minor gods.
athenaartemisapollodemeterherahestiazeusposeidonhadesdionysuspannikemorpheushecatehypnosboreaszephyrosaeolusnotoshermesjanusjanuamphitriteaphroditeerosareshephaestusmercuryplutopomponatritonminervavenusneptunevulcanhebepersephoneproserpinaheliosdelphineus
Minor Greek gods and goddesses had no major followers or cults during the period the Greek god and goddesses were recounted to "classic" mythology.
There were 12 main gods, such as Zeus, Poseidon, Aphrodite and Hermes but there were loads of minor gods, unfortunately i don't know the names of any greek minor gods :( Hope this helps you :D
Greek or Romans ?
both
No not all Greek God's live on Mount Olympus. There are minor gods like Hestia and Janus. They do not live on Mount Olympus, only the major 12 do.
No, Artemis was an Olympian goddess. The Olympians are the main Greek gods, so that would make Artemis a major (not minor) goddess.
12 olympians, hundreds of minor gods
No Greek Gods - Leo is a Lion.
The difference is quite simple. "Olympians" in reference to gods are the greek gods with thrones on Olympus. "Greek Gods" is used in reference to the Olympians and minor gods.
There are tons of minor Greek Gods who receive little or no attention in myths, but of the major Olympians it would have to be Hestia, who was supplanted as one of the 12 by Dionysus.