Here's someone in the same situation as you.
But, in reality, I was able to edit documents and even save them. No Problem at all in other products too like PowerPoint or Excel.
Question 1
Yes, full functions, but it will end (see Q3).
Question 2
Pretty sure it isn't...
Question 3
If you go to the link above, you'll see that for the guy:
On the last day, MS Word 2013 greeted me saying: The Trial of Microsoft Office Professional Plus 2013 is expired. Editing in Word has been disabled.
His "Microsoft Office has finally stopped working. Not that it doesn’t open but editing document functionality has been disabled. You can still open any file in read mode only."
So basically the program became useless. Maybe that answers your third question - Microsoft allows this because the program will become read-only eventually, even though not in 30 days.
I'd advise you to purchase a license as soon as possible, as you're close to the 3 month period too. Otherwise your work might be affected when the day comes. Better safe than sorry.