Hi Schmidt,
The input range for the 6025E board is +/- 10 V, so if your signal (going into the DAQ board) is within this range you are safe. In regards to reducing settling time, you are on the right track. The following link is a great resource when using a voltage follower to reduce the impedance of a transducer.
http://zone.ni.com/devzone/conceptd.nsf/webmain/CD57A73721E0612586256BAE0055CDD9?opendocument&node=dz00000_us
Have a great day!
Brooks W.
National Instruments