H1B Stamping in Mexico and travel with expired H1B visa

[Nahs]

1. My I-797 is valid till end 2018
. My stamped H1B visa in passport has expired mid 2017
3. My Indian passport is valid till 2025
4. My PERM*has been initiated on May, 2017 and is currently in progress.

I want to go for my H1B stamping in Nogales ( or Hermosillo ), Mexico being 3 hours ( 6 hours ) by road from Phoenix, Arizona.

Please advise on the following -

1. Travelling to Mexico on expired visa/valid I-797 combination

2. Recent stamping experience

3. Pre-requisites of additional checklists as compared to getting it stamped from India ( in some forums / experiences delay is reported due to the approval not present in their system ? )

Thanks in advance