Problems editing data on CD-RW

I am glad I found this place in hopes to finally understand CDs and CD drives.
OK-I understand the difference between a CD-R and CD-RW media. I want to use a CD to put some excel spreadsheets on them to send them to other users and have them open the CD and and the spreadsheet and add and save data to the spreadsheet in order to send the CD back to me. I thought by formatting the CD-R using Direct CD that would do it, because I tried it on my computer which has a CD-RW drive and it did it…but there are some users who open their spreadsheets and cannot enter new data to the spreadsheet. Is it because of the type of CD drive they have?
Please help me to understand something that probably should be easy but I am so thoroughly confused. Are there 3 types of drives-CD-ROM, CD-R, and CD-RW? I am sorry if this is a stupid question, but once I feel I understand it the next second I am back to being confused.

The problem with packet writing software like Direct CD is that sometimes they don’t write to discs formatted by a different application, and it can occur even with different versions of the same (for instance if the disc is formatted under a UDF version your partners version doesn’t support).

If you use the CD-RW disc to carry the info both ways and you don’t keep backup copies you’re running a big deal of risk.
Best to transfer to HDD, edit, save and send back the changed files under a dif folder or even using another CD-RW (as you can re-use them), this way the task of your and your partners machines would be only to read the disc and as they would write the return CD-RW using their computers you should have no probs.

Check if the files in the disc (or in the computer, if you copy them to the HDD prior to work on them) allow editing or are marked as read only (right click on file icon - properties - if necessary unmark the read only check box).

Thanks for answering my questions.

In order for the partners machines to be able to write the file they edited on their HDD they would have to have a CD-R or CD-RW drive? Is a CD-ROM drive just read only? I had some instances in which the others would transfer their file to their HDD, edit their info and were unable to write the file to the CD. Just to let you know before this particular project my company is doing went out, we did not poll our users to find out what type of hardware they had. I am pretty sure some of these users are working on older equipment.