PowerShot S50 + WP-DC300

Hi,

I'm interested in WP-DC300 underwater case for my PowerShot S50 but I'd like some information.

In forums I read that the case doesn't permit to turn on/off the camera while in the case, is this correct?

Can the case be used with external strobes or with additional lens (fish eye or macro lens)? If yes, what do you suggest?

Is it safe to dive deeper than 30 mt (100 ft)?

Ciao

Mauro