1. Well i don't like the interface of the Nikon camera's and i'm not a big fan of Canon's aproach to handling. Ain't even looking at Sony so that leaves Pentax for my APS-C needs. I'm however looking into m4/3 system though for my personal photography and for filming. For profesional, we have the Canon 5D mkII, nice camera but for what my partner is mostly doing but for what i'm doing i'm actually looking into 645 systems. And there Pentax is quite atractive at his price.
3. pentax cover of lenses is good enough, it's as simple as that. You can have 3 versions of 70-200 lens like canon but that isn't helping much
As for Ricoh, here in the netherlands they have an reprensentative but they are going to open their own Pentax office now here so that is good news.
Also Rixoh is droppping their name for the consumer camera's so all the camera's will be made under the Pentax name.
Ricoh is really comitting themselves and that's good sign.