Hello there, I'm new here and new to 3d modelling in general.
I hope I'll be able to learn and even help others here in the future~

Anyhow I've been trying to get fast into 3d modelling and I found myself in a few troubles that I'd love to get help with.
My goal was to create an iphone model for the sake of learning but my problems were:

1) Rounding corners of a square
2) For things such as the home button of the phone , Camera, side rounded buttons, I tried using the polygon cylinder tool and combine it with the main mesh, but I had a problem with the home button as it needed to be lower than the main face, an example pic:

After I combined the cylinder with the square, I tried to move the cylinder down to have a rounded hole.. but it just disappeared under the surface.

These are my main issues at the moment,
Thanks in advance