<<< Should I expect the new MAC to have a standard ethernet port so he can just connect to the router as with the PC? >>>
<<< Will he have to do any configuring on the MAC to be able to use my printer, which is USB and connected to my PC, not to the router? (With his current Windows PC we have to make it be on the same "workgroup" as mine.)
I have to admit that I have never had any success in trying to use a "network printer" from the Mac to a printer connected to a PC (although I'm sure it can be done!). Instead, my solution was to use a Belkin USB switch that allows up to four computers to connect to a single USB peripheral.
<<< Will we be able to share documents, (assuming folder sharing enabled as appropriate), or do PCs and MACs not converse? >>>
There is no problem in "sharing" documents, as in transferring them between PC and Mac or vice versa, but to do anything useful they need to be compatible with the programs in both computers. The Mac will open PDF files, RTF files, graphics files and so on, but to open Word or Excel files, for example, would require either the Mac version of Microsoft Office, or something like Open Office which supports the file formats.
<<< If so, will it be easy/wizard driven? >>>
A little networking knowledge will certainly help. It isn't particularly difficult, just different and the Mac doesn't have the sort of setup wizard that Windows has.
When you get the Mac, I or someone else can take you through it step-by-step. The internet is easy, just plug it into a LAN port on the router and off you go!