Typical PM practice for bigger jobs

[Mike Chang]

Hi, I understand that my PM pads the maintenance fee a little and probably doesn't get multiple estimates, which I understand now is probably normal. 

Firstly, Is it typical for PM to allow owners to look for their own contractors if the owner thinks the estimate is too high, where the PM gets skipped altogether? 

Secondly, for larger jobs where multiple estimates is not just a nice-to-have, but required: is it PM's job to look for these estimates and provide invoices? (and I imagine to be explicit about management fee where appropriate?).

Thank you for your help.