I currently have a I797 issued by my company (say - ABC) which is valid till Dec 2, 2014.
I have an approved I140, and consequently an extended 3 yr H-1B via an approved I797 from Dec 3 2014 till Dec 2 2017.

I am planning to travel to India in Oct-end 2014 and would need to do visa stamping.

Questions:
1. Which I797 information should I use in filling out forms for my Visa stamping? Can I use both (I cannot find that option while doing this online) so that I can have a stamped visa till Dec 2017?
2. If I am allowed to use only the current I797 for the Visa Stamping ... could there be an issue with (a) getting my visa stamped (approved). or (b) While crossing Immigrations while entering US back in early Nov 2014, because they may think that I have a valid visa only for another month.
3. I understand that reality and 'on paper' things can be different ... does this situation warrant precaution to not travel outside of the country till my new I797 comes into effect?