H1 Visa expiry on 7-Dec-16, should I extend it before travelling? Currently in India...

Currently I am in India. My petition was approved for 1yr i.e. on 8-Dec-15 and valid till 7-Dec-16. And H1 visa was stamped on 1-Mar-16, but never used/traveled on it, and it is also expiring on 7-Dec-16. Now I need to travel on different project in the same company, so I need to apply for amendment. 1) Because my H1 Visa is valid only for 90+ days, should my company apply for H1 extension along with amendment? Or only amendment is enough to travel? Then later after arriving in US, can I apply for extension before expiry date? 2) If we apply for amendment+extension together, then should I have to wait till USCIS approves and get Visa re-stamped, then only travel to US? OR Can I travel on Acknowledgement/Receipt number of amendment+extension filing, which we may receive in a week time. Thanks in advance.