Canteen recovery from employees salary,

We are appointed out door catering service provider in our company canteen for serving foods. They have charged invoice with GST and we pay to him. Then we will recover Rs.500/- per employees from his salary. In this case please clarify below points.

1) can we avail gst credit on outdoor catering bill?
2) can we require to pay gst on Rs,500/- recover from employees salary ?
3) if we will pay gst on recoveries from employees salary then which value consider?

Please advice.