Can someone answer Battlestar Galactica questions w/o spoilers?

I am in the middle of season 2, so please don't answer questions with info from later seasons. Just say, "You'll find out later."

1. Why is Kobol uninhabited?

2. Why are they still looking for Earth when they've found Kobol? Do they expect Earth to be inhabited by people capable of fighting the Cylons for them? Was Earth supposedly colonized by Kobol or the other way round?

3. What's up with Tricia Helfer's character? Can all Cylons cause hallucinations in any human? Why don't they use that power all the time?

4. Early on, there was some substance on a space station that adversely affected a Cylon. Adama figured it out, but this info was not used to make a Cylon detector. Was that ever explained?

5. Galactica can detect ships leaving the convoy. How did Lucy Lawless (Season 2, Episode 8) get away to report in person to the Cylons?

*Bonus. How can people smoke on a spaceship that has no secure source of oxygen? Are they growing tobacco on one of the ships instead of food? Is the show funded by Phillip Morris?

Thanks.