As usual, a little common sense goes a long way, if you can find it. Drill only in the middle and don't put too many holes near mid-span. If the hole must be larger than 1/3 of the height, use a plywood backer at least 3x the height, glued and screwed.

If you ask the contractor (or anyone, really), get the answer in writing even if he's an engineer.

WRT plumbers- have, or are?

Sure there is.

There is pipe fill that can be used for holes.

Also, there is code about distance from edge and requirements for strike plates if you get closer to edge. Drywallers also have code for length of screws depending the material they are hanging (try asking them about it -- I dare you).

There is also maximum drill size for every type of lumber, be it load, non-load bearing, structural and engineered.

We usually put conduit sleeves in concrete walls/floors and plastic sleeves in metal studs but nothing through wood studs. As other have said we usually as put 3M fire proofing at penetrations to another room/floor but thats about it.