I signed a lease, found out my circumstances have changed. Told rental agency, less than 24 hours later, I would like out of lease. Am I entitled to my rent and deposit refunded

The renting of property does not fall under the 3 day recision law. You signed a legal agreement and they can hold you too it. If the lease is a one year lease, you are responsible to pay the rent until the property is rented to someone else or the lease ends. Ask if they will allow you to buy out the lease.

No, you may work out a buy out on the lease since you have not moved in, but the only way out of a legally signed lease is by the terms of the lease.

I would think there'd be a grace period of about 3 days in which you could cancel the lease.