Buses - I have never got one - as car hire is so cheap. Taxi from PDC to PB is approx 35-40E. YOu can hire a car for £70 a day.
Wow - just thats the cheapest I've seen in ages - £58.60 for a weeks car hire at this short notice too.
Taking cash over - well I have said many times before that you are a mug taking over large amounts.
What will you gain? A rate of 1.45 as opposed to 1.42?
So you take £500 with you? Well done an extra 15 euros - at what risk? Losing all that cash or having it nicked? Plus the places that offer these "bumper" ratessupport all kinds of nefarious activities on the island.
No one likes to be ripped off but get yourself a nationwide or post office credit card who don't charge for overseas stuff then your sorted.