The answer to every one of those questions is the exact same thing.

It's a matter of preference.

Some guys lather on the soap, some in a bowl or moss-type scuttle, some face lather.

Some of the guys who face lather will load up their brushes in whatever dish they happen to keep their soap in, while a few of us (like me) use an old-fashioned scuttle to keep hot water in for the brush and load up the soap.

The same is true for keeping different bowls/scuttles/brushes for each soap.

There just isn't a "right" answer.