visitor visa for working parents

Hi,

My Dad is working in Dubai and my mom is a house maker back in India. I would like to take b2 visa for both of them when my dad comes to india next month for a 2 month vacation.

I got few queries :-

  1. As per my understanding the docs my dad needs to get from his present company would be Employment letter and salary stubs.

  2. Would he have to get a leave sanction letter? this would be least possible as the travel dates are not planned and it would be mostly next year.

3)Will there be any issues if the intended date of travel is a year ahead of the interview

  1. Also my inlaws would be attending visa interview by sept first week, so would there be any issue if my parents too go for the interview in one months gap.

Note: both of their travel date to US would be different. In laws would be travelling soon if the visa is approved.

Also appreciate, if someone had a similar experience.

Thanks & Regards,

Hema