Is the biting point high, or very high? Mine was high when I bought it, assuming that was ok, clutch went 2000 miles later. If there is any member local willing to check it for you well worth driving over their way
DA stands for Dual Action, its a machine which makes cleaning a whole lot easier. You can do work by hand, but it will only have so much effect as it will be impossible to create the friction and heat needed to properly remove the swirls.
A decent mid range DA is around the £100 mark, or you could try contact one of the detailing guys on here?