The answer to "what should they play?", I think, is "as little as possible". Dance tunes, particularly English ones, tend to have a very square, solid, percussively rather boring beat; jazzing it up with syncopation and cross-rhythms is tempting and can be fun, but it's liable to stretch the music out of shape rather than supporting it (I swear one evening we ended up playing Dennis Murphy's Salsa - which was fun in itself, but dancing to it might have been a bit interesting!).

At the bass end I think the most we need on the average tune is
BONG
...
BONG
...
BONG
...
[and] BONG BONG [and]
BONG
...

and so on. So basically we need someone who (a) can lay hands on a big drum (b) has a good sense of time and (c) doesn't get bored easily.