We are planning a vacation in june 11. There were a few concerns that i was wondering if anyone can tackle for us

1)how is the weather in june? I heard its rainy season so does it rain all the time or more like couple of hours etc?
2)i really want the beachfront room, thats a seller for me. But i read that there is no guarantee on rooms. Is that true? If yes then how does it work? I pay for the garden view room and then can upgrade upon arrival? Any reason why i can't just book and pay for the beachfront room?

any help/suggestions will be great.