^Messed up on my poll. Ignore it.^

I thought that tombstone looked like an interesting donation feature but the donate info page didn't say much about it. So here are a bunch of questions that would really help me if you'd answer them. Thank you.

1. Will a chest spawn for tombstone in a town that you do not hold perms to?
2. Will a chest spawn in all worlds?
3. Will a chest spawn in lava?
4. Does tombstone pretty much make you invincible from losing items.
5. If you're one of those noobs who always falls in lava, ect. would you recommend getting tombstone?
6 Is it worth it?
7. So if I have tombstone my items cannot burn when I die, right?

Thanks for the help!