Does the 27 inch iMac have a DVD/CD drive?

The last iMacs with an internal optical drive were the 2011 models. You will need an external DVD drive. Apple still makes the olde USB SuperDrive but its compatibility with newer Macs is not clear based on reports here.

Should I have a need for a modern external DVD drive for my 2017 iMac, I will be looking at this:

https://eshop.macsales.com/item/OWC/MR3USD24/

It is USB3 so should be faster than the USB2Apple SuperDrive, and costs about the same.

I have a 27" iMac and have several DVD drives (Apple, Samsung and others) and all work fine. Just be sure to connect directly to Mac and not through a hub.

Well, the performance of an entry-level 24" is far superior to an entry-level 27" due to the amazing Apple Silicon M1 chip. The 24" (replacing the 21.5) was also very recently redesigned.

Cheers,

Jack

...entry-level 24" is far superior...

Jack, have you seen third-party benchmarks yet on which to base that? Would love to have the link if you can provide it.

If the OP is using the computer as a TV as well, I think that screen size takes precedence over actual speed, entry level or not. My 2017 iMac 27 with the quad-core i7 processor an Apple SSD is still a screamer.

These Geekbench 5 scores from the MacTracker database show the M1 MacBook Pro and the Mac Mini (score is the same as the MBP) only slightly faster, not "far superior," to the mid-priced iMac 27 with Intel processor:

I have an M1 MacBook Pro. It's quite nice but not far superior to models from two years ago.

If I was in your boat, I would choose the new 24" iMac.

Cheers,

Jack

You are most welcome! Mrs AJ is very fond of purple so I am considering the same model to replace her 2011 iMac. Whichever you decide, you will need an external drive.