What do you know about biodegradable plastic sheets?

Here are my questions:

1. Do they start to disintegrate over time at room temperature? what about if humidity is high?

2. Could you have a roll that would tear like wax paper? I would actually want it to be like the plastic for cheap trash bags or supermarket bags, or a little stiffer. Not sticky like Saran wrap. Does that exist, is there all sorts of plastic that is biodegradable?

3. Another option is sheets in a package about 10“X15” each individual sheet, maybe a package of 10 or 20. Can they be scented? Would they stick together after a while? Bendable, but flatten out with no problem, no crease created.

4. How long until it decomposes in landfills?

5. Can you compost it?

6. Is it expensive?

7. Is there another material that would block smells well that is cheap and biodegradable?