International Pass to India

Hi I'm planning to travel for work to India next week. I'm on Magenta Max plan. I'm looking to buy 10 day pass for 35 dollars.

My questions are -

Can I add more data before the end of 10 days? Or I might have to compliment using an data only e-sim from 3rd party vendor?
Can I get seperate bill from T-mobile for the pass? For expense reasons. My work already pays a portion of my cellphone bill so I can't use the same bill twice for monthly & pass.
While in India can I call domestic Indian cellphones/landlines using my Tmobile plan on roaming without any extra charges?
Is there any way to check the data usage out of International plan portion?

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