Venom is an anti-hero in the Spider-Man franchise. He is one of Spider-Man's archenemies later turned rival. The name has belonged to several different hosts over the years, which means that Venom is indeed the identity of this particular alien Symbiote. The Symbiote named itself Venom and considered itself as a venom for Spider-Man.
Sonic and Heat: The Venom symbiote, like all others of its kind, is extremely vulnerable to heat and sonic based attacks. They can cause the symbiote physical pain and discomfort, whereas "more powerful" attacks might be completely ineffective.
Oddly, it was shown that Venom doesn't like being called a "parasite", even by Eddie (as they are arguing about this at the end of the film).
It was also shown that Venom did like Anne and care about her; this could be one of the reasons why Venom didn't kill her while re-swapping into Eddie (which is unlikely as a symbiote would have to kill its host if he/she wasn't suitable to their nature or when swapping to another host).