Couple of queries

I've got a couple of questions regarding my 2002 Multipla JTD ELX.

1. Occasionally the front brake warning light illuminates but it's not when I'm braking but more cruising speed. I've had my pad's checked and there is about 25% life left on them. Any ideas what could be wrong?

2. Driving my multi the other day these was an almighty clunk from underneath and the car served sort of left and right. Speaking to someone on the phone they think it is my suspension bushes. Anyone got an idea ofhow much this could cost roughly?

Any help or advice is greatly appreciated, my 4yr old son and me both love our multi and have nicknamed it the "funbus". I just hate it when things go wrong with it, especially when I have it serviced regularly.