the surface pro 4 and the 2017 surface have 1 usb port which is usb-a. you can plug in an external cd drive to the usb-a port. there isnt a surface pro 4 with a cd drive (cds are becoming obsolete these days and now that i think about it ive never seen a tablet that has a cd drive). as for the keyboard and mouse thing, its bluetooth or usb adapter if the keyboard and mouse you buy has a usb adapter. just as an example here is a keyboard/mouse combo that uses a usb 2.0 adapter
https://forums.windowscentral.com/e?...token=MAjJ9ska . the good thing with the logitech keyboard/mouse combo at least, is that only 1 adapter is required and the keyboard and mouse can connect to that one adapter. the downside to this method is, if you want to use an external cd drive, keyboard/mouse usb adapter, and printer/scanner that requires usb (i saw your other post regarding the printer/scanner and usb) then youd have to buy something that gives you more usb ports to plug everything in to. of course, if you go the bluetooth keyboard/mouse and wireless printer path, then you can plug in just the external cd drive without any problems.
