No, Lavoids aren't bent on destroying the universe. I think all of the things in saying: "Lavos is the ruler and destroyer of the Planet" in 2300 AD are not true. Lavoids are a race that require DNA and energy to survive. The best source of such resources are planets. He erupts in 1999 AD, that's just a really big yawn. He sits on Death Peak, making his spawn, so people think he's like sitting on his throne of doom.
At least when Lavos crashed, he wasn't intellegent and was just an hungry animal. What happaned after all that, I guess Lavos can become a evil genius. Hadriel actually made a huge thread about this at Chronicles, that "Lavos the Dark Lord" monster of a thread. Anyways, he's definetly smart in CC: He's got both Schala and the Dragon God as sources of intellect. He then used the Flame to create another Arbiter, and the rest is history.