How do I change the Battery ?

You can change the battery in it. You have to pull the four pins on the side holding the strap on the watch. You can do that by taking a knife or small screw driver and inserting it between the band and the plastic case. Sort of twist the knife and work the screws out. When you get just the head of the screw out you can pull them out with your fingers or plyers. Once the band is off it will let you see the four screws holding the back on the watch.

Will it survive dipping in water multiple times and soaked?

I enjoy swimming in both lakes and pools, and mine has stood up well against both. I haven't tried operating it under water yet, so i don't how it would do with that.

Does this watch use a button replacement battery if so what is the#?

Do not know- any watch repair place will likely have the correct battery.

Whenever I hit a button it beeps. Is there any way to stop that?

“In normal display mode press MODE key twice enter the alarm （ALM） clock mode, perss START key for Noise and on time switching and ON/OFF setting. Only ‘AL’ icon, Noise is said to open: Only ‘CH’ icon,Say to open on time: the icon all show,Noise is said to have time for the open: No icon and all the close.”