Contractor for Finished Basement

we are looking for a contractor who can do some work on our (finished)basement to allow it to be used as an office.

1. add a bathroom- the basement is below sewage line so as I understand it we need a plumber with a special license to put special fixtures with pumps in.

2. a separate entrance- right now the basement just has a hatch with a very steep, low stair case, we need to excavate more and put in a proper stair and door, with appropriate drainage.

3. possibly some work on a “machine room” for computers- some drywall, air conditioning, and additional electric line work.

thanks for any recommendations