[peachii]

You can keep it in the bag just open it and change the water everyday or buy a tupperware container or jar to put it in and change the water. If you leave it closed up the entire time it will start to smell pretty bad by the time you get it home.

 

[peachii]

Java moss is pretty tough, it should be ok so long as it's not in the dark the entire time.

Tap water should be fine but if you are concerned you can use bottled. I usually rinse new moss out in tap water without declorinator when I get it.