Deductions & credits

I literally made $0. ZE-RO yes I made no money this year. We have NO earnings, none whatsoever! Yay! 

 

But I guess I don't understand the $1 of fake interest.

What would happen if I put $0 instead of $1, what would happen? 

Or say i were to paper file without TT, ( i don't plan to) but if I put $0 would that break something?

 

Lastly, I'm not sure 50/50 if we paid our property tax, the bill is $1500. I have to ask my wife.

But If we did, would that change anything regarding this refund? Or would that not matter?