How short selling work?

Hi guys,

As we all know DMP is currently one of the most shorted stock ASX wide. https://www.shortman.com.au/stock?q=DMP

I understand how short selling work in theory, but not much in real world. Here're some of the questions I have, if anyone could answer these questions it'd be greatly appreciated

- Once they borrowed the shares from a lender (e.g. UBS), how does lender charge the borrower? by some interest rate or what?

- If the borrower is stuck in a share and can't return with a profit, is there normally a deadline when they have to return the borrowed shares? If not, will they be charged extra for borrowing for a long period?

The reason i asked these questions is because even though DMP is heavily shorted, it seems it has strong support on the current level and I expect the current short level to drop significantly when the share buy back starts on 29th Aug which is only 3 trading days to go. I'd love to see the shorters to be burnt but without knowing the theory behind I can't be so certain so just trying to get some more understanding in this area.

Cheers,
PIK