Return journey between HK airport and Butterfly on Prat Boutique hotel

We are group of 4.

From airport to Hotel - AE ticket packages for 4 will be the most economical. I need to take AE train to Kowloon station and take bus line. Which route and i should stop at which stop that is nearest to the hotel? It is only free if I take AE train from airport?

From Hotel to airport - should i buy the AE train ticket in advance to enjoy the free bus services from hotel to airport? Or i could purchase the AE train ticket from the bus itself?

Thanks