Thruster & Quad - advise please

Hi all just purchased a 6 6 webber Pulse with the 5 fin option - I have never surfed a quad and my new board only came with 3 fins! 
When is a quad better over a thruster set up? what are the advabtages / disadvantages with the diffrent set ups
When in a quad set up are all 4 fins the same dimensions or should the front 2 be bigger than the back 2???
Any advise on quad set us would be apprecaited - I think i read theay are better in small junky surf????
advise please please please

When is a quad better over a thruster set up? what are the advabtages / disadvantages with the diffrent set ups
When in a quad set up are all 4 fins the same dimensions or should the front 2 be bigger than the back 2???
Any advise on quad set us would be apprecaited - I think i read theay are better in small junky surf????
advise please please please