Quote: " I saw that DGSDK can’t create games for consoles (PS2, XBOX, GC), will that ever be possible?"
No. DGSDK uses Directx and consoles use...something else.
Quote: "Is DGSDK capable to use other app that DB (DBPro) can use?"
It has support for the same files and support for the plugins is being added. So yes.
Quote: "When will the commercial version come out and how much will it cost?"
Umm.
Quote: "What are the benefits of DGSDK from DBPro? (only the speed or something more?)"
You get to use C,C++ and thier compilers and IDEs. That means You get a better languaje, a better IDE and a better compiler.
EDIT: Darn DavidT beat me

A bargain at 900000€ second hand
Libera tu mente y te liberaras.