So… summarizing the requirements:
- Talk to MS Office and Exel: Given MS politics no other program will work reliable. People have tried and failed over and over again.
- does E-Mail. I can recommend Thunderbird
I can recommend LibreOffice
For printing, as mentioned the only way to get reliable output is PDF (which can't be edited).
If you want to edit the same file on different computers, you have to use the same software and the same software version. There is no other solution.
That can mean that you have to install MS Office, or that they have to install LibreOffice.