I had not accounted for this big of water bill charge - looking for way to minimize/cover this.Any help/insight will be greatly appreciated!

That said, if I could rent the place such that there was no extended gap between tenants, is it common place to charge the fee they agreed to in signing the lease?

We also charge 20% of gross but I like to be on the lesser side so that the owner makes more and we also strive to get the highest nightly rate that we can for our owners and optimize their properties for max ROI so 20% is sufficient for us at this point.

On Robert Kiyosaki's Cashflow game we would always ask when it was someone's turn to pick a card: "Small deal or big deal?"

He used to charge that during the market crash... when materials are a lot cheaper and no one was hiring.

This is why your QI usually charges more for an owner carry note. 

All will depend on the exact fees the condo is charging and location. 

In Massachusetts you can not charge a late fee until after 30 days.

If I upload my transactions from my credit card and categorize it as business, do I ALSO need to upload a receipt for that transaction too?

But don't get me wrong, I'm sure there's attorney's that would love to charge you to write LLC's for you.