As far as I know if your H1B gets terminated, you are out of status. I am not sure if there is any grace period after H1B termination. Other Sajhaites might be able to share their expertise on "grace period".  So termination sounds like a bad idea. Say your H1B did get terminated, if you want to get F1/F2, you should do it immediately. USCIS may not approve your change to new status if there is a significant gap between H1B termination and you applying for a new status.

If you want a Change of Status(COS) to F1/F2 while in H1B, may be F2 is the quickest/easiest. I do not know much about F2. But I do know about changing status from H1B to F1 because I had to do it.
To change status to F1, first you have to have an I-20, then you have two options.
1. Apply for Change of status from within US. This process may take upto a few months. Just because you have an I-20 does not mean your status automatically changes to F1. You have to fill out paperwork to do so. And while your case is not approved, you cannot join school as a FULL TIME student. You are allowed to take part time classes on your H1B, but no full time student status.
2. Go outside of US, apply for a new F1 visa with the new I-20. Stamping of a new visa on your passport automatically changes your status to F1. I chose this option.

Hopefully this helps.