New Pedals w/ Tri Fly Shoes

Thank you!  I'll take my shoes to the bike shop and see what they have.  Still have my "new bike purchase 10% off everything discount".  When I told them I currently used SPD mountain bike type pedals/cleats, I think they thought that was all my shoes were compatible with (and I wasn't sure either).  So they initially suggested I think about getting new shoes that didn't look very tri friendly to go w/ some road pedals.

I know there are a kazillion pedals out there, but any input on favorites would be much appreciated.  In trying to understand the factors am I understanding correctly the following? 

More float is good (at least to a point) in terms of lessening knee injury potential? 

More contact surface good for evening out pressure the foot (or does it matter since my shoes have a very hard sole)?

Less weight is good, but thinking not very significant to me at this stage (or perhaps ever)? 

You can use virtually any road pedals, since the shoes have the three-hole pattern that is pretty standard.  Most systems have some float (ex. look has cleats that give 6deg. of float, which is fine).  Don't worry about the contact/platform issue; all major road pedal systems (Look, Shimano, Time, Speedplay) have more than enough; if you were fine using SPD pedals this isn't going to be a problem.

I'm personally a fan of Speedplay Zeroes.  Light, and with adjustable float.