User Manual Philips HX9352/04 Sonicare DiamondClean Electric Toothbrush

Yes this toothbrush can be used in the shower. I rinse off the brush and handle every time I use it so it gets completely wet and it has no adverse effect on the toothbrush at all. This is an excellent toothbrush.

No. It has a timer though, so it takes you from agreesive brush, to a lighter one. It's a great brush.

The travel case stopped holding a charge. the real problem was that the toothbrush stopped working consistently. the movement of the brush head became intermittent.

Yes, I use my white diamond head on my boyfriends black diamond all the time. They are interchangeable

No. I'm not familiar with that feature. You really shouldn't be pressing. You just move the brush over each quadrant, letting the brush do the work for you.