Les - PA up a lead musician and the caller only. A stand alone mike is good so you can vary the lead muso. Have some fold back towards the rest of the musos.
In practice sessions deliberately play 3 As 4 Bs and an obvious slow down ending. Encourage listening. Try playing a 6/8 as a waltz. etc. To encourage listening skills ask some of the band sometimes to just listen and then Comment on
did you all want to tap your feet? If not your doing something very wrong.
did we have a balance between top / middle / base line ( if not some instruments can go higher/ lower)
was there a balance between loudness of instruments/ percussion. Could you hear each instrument?
- some groups of instruments need to play louder/quieter

Look on you tube for the speed of dances - you'll find quite a variation but within limits. Some dance books will give the metronome speed.
FloraG