Need Help on Few Thing for H1B Stamping

I Need Clarfication on below.

1.My H1B is approved with US based Employer, Right Now am still working for TCS from 3 months and i have overal 8.6 yrs of experience. Do i need to carry Experience letter from TCS as am still working i may not get that or Only offer letter is sufficient.

  1. Am working in Chennai and can i go to Hyderabad for Stamping as i have been in chennai only for 3 months

3.My H1B is for In House project, what type of questions and documentation will be asked.

any help on above is highly appreciated