take a look at this:
http://www.dtekcustoms.com/index.asp...PROD&ProdID=17
It maximizes the radiator surface area that the fan can affect. They use long thin bolts that go through the fins to mount the fan and shroud. Other people have found tupperware or glad containers that fit just as well and are cheaper to get.
As for blowing or sucking, it doesn't matter. My preference is to suck air through. I mount my rad against the front wall of my case with the fan behind. It represents a smaller aspect inside the case than to have the rad sitting so far in.