H1B Entering US with a stamped visa when I have my new I-797 approved

[rony3472]

My current H1B stamped visa will be expiring on Dec 15, 2019. I got my I-797 extension for 3 months only (Till Mar 31st, 2020). I am visiting India for a month and planning to go back on Nov 4th. Since I got the extension only for 3 months, I am not stamping my visa. I would like to enter US with my stamped visa.
1. What are the possible questions I might have to encounter?
2. Can I request the immigration officer to issue the new I-94 till Mar 31st? Or the officer will give till Dec 15 irrespective of any request.