ported box dimensions

I'm trying to plan a box for my truck but I'm confused on the ports.  First, does the shape of the port make a difference in performance?  Not circular vs slotted but a square port vs a rectangular at the same volume.  Also, how far in the box should the port go?  I haven't seen anything that specifies this in my manual.  Thanks

Thanks man.  I'd almost decided to stick with the boxes I had until I heard a friends 2 kicker cvrs in kicker ported box with an alpine 500 watt amp blow my doodie out the water.  Just need a couple more questions answered before I start designing and building.  Is it better to have seperate the box so each sub has it's own air space or let them run together.  Also, could someone tell me how to measure the depth of a port?  Do you include where it turns at the bottom of the box or what.  And one more thing, how do I tune the port.  I think the size of the port changes what the tune of the box is but I don't have a chart or anything to tell me.  I have winsid but alpine type r's arent one of the drivers it lists. 

Got the wood and everything but I'm starting to second guess my design.  I had originally planned one port in the middle going to both sections but I don't know if that would decrease my box volume because the subs would hardly share any air.  So now I'm thinking about having one port on the side of the box and the  two subs in their own little section.  Would this be more efficient?