As for how long you can run Office 11? How long did you run OS 9?
On my Apple iMac DV SE G3 I ran OS 9 from 2000 to 2011 (and then until mid-2017 when I finally recycled it).
I used OS 9 on other (institutional) Macs for a while before that (ie, since its inception).
So I'm good to squeeze out however much time I might have with El Capitan and perforce Office for the Mac 2011.
