Will they interoperate nicely? File sharing, printer sharing, media sharing etc? Or is it a headache?

They can do. Our office is on a server network and both Macs and Windows work fine (sharing files, places etc as well as printing to the same destinations).

I use PCs in a Mac house, and have found no problems. The worst thing that can happen is that even if I use MS Word on both computers, sometimes an intricately formatted paper can lose some of the more subtle formatting in translation. But honestly, in the 8 years I have been using both, that has never posed a serious obstacle.

Only issue might be that everybody wants to use the mac and not the pcs!

Not going to happen 🙂

I’ve worked in studio environments for years with Mac/Windows machines cohabiting perfectly. Especially if you install VMWare or Parallels and stick Windows of some flavour or other on the Mac. Issues with document formatting changing between platforms is usually down to there being subtle differences between font character widths. Otherwise you shouldn’t have any significant issues at all.