As far as I know, the amount of the bills is based on the value of the objects on your lot. I don't think you should get any bills if your lot is empty, but you will get bills if you have even one object. I once had a lot with only one or two items and I would get bills for §3.
Well, it's actually based on the value of the lot, whether there are items on it or not. So if the lot is worth enough simoleans, you'd still have bills, especially with the 60X60 lot.
Even if you don't have anything on your lot, bills come, bills stay unpaid, REPOman comes, What does he take?
I believe he takes it straight from your "bank account," meaning the simoleans you actually have to spend.