Lpc2000

I have a project that was setup for a 5v AVR that I would like to 
convert to an LPC2294.
  
Q1: Is it better to use a simple voltage divider on the GPIO Input (to 
get 3.3v) or should I leave it at 5v? (I know it says 5v "tolerant", 
but is it safer at 3.3v)

Q2: On GPIO outputs, can I use a pullup to get 5v, or should I use a 
buffer, ULN2003, etc.? (again, I am concerned with reliability)

Q3: On the sensors designed for 5v operation, is an op-amp with gain 
<1 the best solution to achieve 0-3.3 scale?

Q4: On the ADC inputs, I have read that you should ues pullups even if 
they are not in use.... does this apply to all LPC? 

Thank you very much for any response!
  Daniel.