Anyone know about First Home Saver Account?

Question 1. If I buy an IP which will not become my main residence, do I still have to close my account?

Question 2. I wish to buy a property within 4 years of opening the account. The rules state that 4 years must pass before you can access the money, so they would freeze the account until 4 years is up, and then release the money, and you must put it "toward your mortgage".

What if i have an interest only account? I cant put it "toward my mortgage". Can i put it in my offset account instead?

Thanks!