Ceiling Speakers In Bathroom

[Renovation]

I want to listen to the radio in my en suite.

Nothing hi tech just intending to install a couple of 6" speakers in the ceiling and wire them to my mini hi fi in the bedroom.

Like these:

http://www.ebay.co.uk/itm/Water-Resistant-Speakers...

My questions are:

If I don't try to emulate a rock concert will the ceiling remain crack free ?
Will I need to box them in - because otherwise surely all the other upstairs rooms will hear them through the attic space
Does anyone have a recommendation on the speakers - again nothing too fancy required it's only a 6'x10' room
Presumably a simple speaker changeover switch is required between the bedroom and bathroom - any suggestions ?

[Renovation]

I'm aware this is very much the budget option but it's just for when I'm having a shower so as long as they're better than a £10 radio they'll be fine.

I used to spend a fortune upgrading my car stereos etc but now I'm older as long as I can hear it, it's fine.