Should go for F1 extension or H1b stamping?

[h1visaApplicant]

I have both H1b and OPT extension approved but have to go to India before Oct(h1b start date). Could someone please answers my questions below?

 

Below are the details of my situation

1.       OPT approved (F1 renewal required)

2.       H1B approved starting Oct 1

3.       Going to India in Aug

 

In this situation: 

1. Can I attend F1 stamping? 

 

a.       I understand I will be not able to come back to US till Oct 1(or 10 days before) if I go for H1b stamping.

2.       If I choose to attend F1 stamping first and it is rejected – would you think it might affect my H1b stamping interview ?