Glad you got everything working. Now comes the fun without the frustration! :-)
Before you go buy any modern CD drive, make sure you get one that is not too deep from front to back. Some (a lot actually) are so deep they will not push back all the way into the 4000 and leave room for the cabling and a clean airflow to the power supply.
I found a CD-R burner made by LiteOn that fit perfectly. There's not much difference in price between a CD reader and writer these days, so might as well get a burner, I say.
You can download MakeCD software with free registration now. Search the Amiga.org news items from the past year for info on downloading and registering MakeCD. I found the program rather confusing at first, but finally I got the hang of it. It's certainly not as intuitive as something like Toast on Mac.
Have fun.