Effective tenant management involves clear communication, lease review, and considering parent co-signers for college student tenants.

Most everyone is comfortable with holding a property for a year. 

Do they have to pay taxes in the US and do I need to withhold anything from them before paying their interests or will they report their gain in their home country and pay taxes there and nothing in the US?

The best is when they move in and immediately begin making maintenance demands for things they broke themselves, or because some man they lied about not being on the lease is living there and broke it, or one of their endless supply of children broke it  and it's like you still owe like a grand from your deposit maybe don't take such a tone when you fuss over maintenance issues you created in the first place - but God forbid you withhold whatever pithy deposit they did manage to cough up for damages because they go full throttle Jerry Springer guest in 2.2 seconds. 

She managed the real estate properties that my parents hold.

My parents had rentals and they looked at them differently than I did (interest rates were also different).You ultimately need to be comfortable doing what you are doing and educated in it. 

Books have really been good for them, because sometimes kids don't like having their parents "tell" what to do lol.

Looks like a helicopter parent situation.

We are still diligently screening the tenants and they are agreeable to using their parents to cosign in one way or another.Can I have one parent cosign for the group if they agree or does each individual renter need a cosigner?

I'm a parent of college age kids.