On a standard BT phone line that supports a PDQ machine for direct credit card sales, can you also have a broadband line running at the same time? Just checking if I need a 2nd phone line for broadband.....

AFAIK PDQ machines use a dialup modem connection (all the ones I've seen have, though it's been a couple of years I must admit) so provided you've got it running through a microfilter you should be fine to have broadband on the same line.