if you put /home on its own partition it keeps all your files, pictures,music etc totally separate from the OS, so if the OS crashes or you want to change it you can without upsetting your data,
also allows you to copy your files [in one massive block] to somewhere else if you want, or, if windoze ever gets the ability to read a modern filesystem, it can access your files too,
I actually have a FAT32 partition on one of my systems for the wife to keep work stuff on[her work lappie is W7]
its not a biggie, but, if you are thinking of keeping it as an OS then Id deffo re-install at some point before you make too many changes or save too many files.
is MSoffice really that different from LibreOffice ?
go to software centre,
install WINE & playonLinux
when you download the .exe , try and open it, and WINE/PoL should just do its stuff .
be aware, ive had loadsa trouble with Wine and .dll files in the past , there are workarounds, but for me, not worth the hassle, open/libre office does all I need.