1:
Money is usually uncountable, but "moneys" does exist. You can use it to sound a bit funny (I have lots of moneys = I have a lot of coins and bills) or to use it as a substitute for "currencies", but these usages of "moneys" are more informal/casual.
2:
Match money with singular verbs since it's a singular noun, and refer to money as "it".
I'd say: I've spent all my money. It's short, simple, direct, and clear.
You could even say, "I'm broke", with a smile to be humorous.
Edit:
"Monies" is more common than "moneys"; therefore it's deemed as "correct".