TDS rate.......?

For doctors 10% u/s 194J since they are professionals.

If engineers working as professional then 10% or else if working on contract basis then 2% or 1%( in case of individual or HUF) u/s 194C

It depends on how these persons engaged with us

If They engaged as regular employees (regular terms of employment) irrespective of their profession they will be considered as the employees and TDS will deducted under section 192B

If those professionals (doctors,engineers) engaging with us on contract basis then considering their professional work TDS will have to be deducted under section 194J @ 10% 

concept of 194C anyway won't considered. because service provided by them is a kind of professional work only.