Newbie seeks answers to V70 D5

Hello together, I would like to buy a Volvo V70 D5 with 163 or 185 hp. I have some questions about this: Since it is supposed to be an automatic, I noticed that there are 5-speed and 6-speed automatic transmissions. Often, however, only in the text “Automatic” can I see by anything, how much gears the good part has ? And what is definitely better? Are there serious differences between the two motors – is the extra price for a mod 2006 compared to a mod2005 with “only” 163P I would like to take a 2005 ́er with a little snap-off automatic, full leather and telephone. BUT a Russian particle filter I would actually like to answer thanks for a few.