I wouldn't worry about the noise or the steam, both are common traits on these bikes.
The noise is most likely the cam chain, and is noisy even when properly adjusted. The noise goes down significantly after the bike heats up.
The steam from the exhaust is normal. If you had a head gasket leak, you would see some very clear signs of problems.
-tons of steam from the exhaust, not just a little, looks like a steam jet
-lots of coolant loss, coolant needs to be topped off every few days
-running temp is very high, and you hit 250 while sitting at a stop light
These bikes run a little rough, but can take immense amounts of punishment. As long as you keep up on the oil changes and don't hit the rev limiter every time you ride, you should be able to enjoy the bike for years.
2006 ZX-10R :: 68,000 miles and still one hell of a ride