I am trying to answer based on my understanding. This is my view, NOT necessarily what is correct.

1.The only benefit to H1B holder with applying TPS would be able to change employer and no requirement of H1B by new sponsor. The caution is you need to apply for new H1B at the end of TPS and will go through H1B lottery in that case.

2. No. You didn't mentioned which stage of EB2 you are though.

3. Yes. I don;t see much benefit though. If in case you lose your H1B by being laid off or leaving work. I suppose you want to have applied EAD day 1 such that you can look for potential employer.

4. You apply for TPS form i-821 .i.e. you provide an intent to apply for TPS. USCIS decides if you are eligible and approves and you are registered for TPS. http://www.uscis.gov/sites/default/files/files/form/i-821.pdf

5.No. But you need to satisfy your H1B requirements continuously to have H1B status once TPS ends.

6. No. Just remember your wife MUST apply as H4 or H1b dependent status at Kathmandu Embassy. Since TPS doesn't have any derivative. So in case you want to just have TPS status and drop H1B , your wife visa status should stand on its own.

7. You don;t need to apply for AP if you continue to maintain H1B status and following it's requirements. TPS would be just as a back up if in case something happens to your H1B. No. Just remember having VISA is not enough to enter USA. You can;t use your H1B visa to enter while you have a status of TPS.

8. TPS defines you need to have continuous present since June 24th . However, a short trip would be okey. So you should be OK for a short trip to Nepal.

9. TPS doesn;t protects your H1b status. They are separate thing. You can resort to TPS if you are laid off from current employer. But then if you don;t file H1b with your new employer you need to refile H1b at end of TPS and subject to H1b cap.