Black stains on aluminium+teflon griddle

Tomatoes specifically will not damage your teflon pan any more than any other cold, wet vegetable. Teflon was used to store a form of uranium in the Manhattan Project because it's so nonreactive. Without it, uranium hexafluoride would eat through storage containers.

It sounds like you were also talking about thermal shock--which you can observe with a hot glass dropped in cold water. That happens on a very, very small scale with pans and food-to-be-heated. I think other factors--like scratching from spatulas and accidental overheating--would wear out the pan far, far sooner.

1. Ceramic pans are more non-stick than PTFE. They don't need oil.
2. Ceramic pans are less durable. They fail within a few months of use.
3. Ceramic pans don't scratch, they are too hard.
4. No, don't throw it away. They don't contain the halogen elements found in PTFE.
5. I wouldn't say so. Mine and my mother's failed earlier, and I've read many reports saying the same. 6-9 months seems to be a common period for them keeping their non-stick properties.
6. Use whatever makes it clean. I prefer to use standard detergent.
7. You are cautioned against ingesting PTFE. This is only relevant after scratching. PTFE is chemically extremely durable (that's why it's nonstick) and will not enter the food unless physically damaged.