hi there
can someone please remind me how doweling works? every how many inches do i need dowels and then a cake board on top? and then do i dowel again THROUGH the cake board or just layers with dowels through it?
thanks for all your help guys!

http://www.wilton.com/cakes/tiered-cakes/dowel-rod-construction.cfm

For every 4" of cake (basically a tier), you should have a cake board for support. Dowels (or straws) should be used for support when stacking and like the link the PP gave you shows, they would be placed within the diameter of the tier being placed above so the cake board rests on the dowels.

As for center dowling, I always dowel 3 tiers and higher. However, if a two tiered cake is travelling far and I'm not delivering it, I will center dowel a two tier.

I prefer the SPS unless I am going straight up. In that case I start with the dowel in the base and put my cakes over it, then for every 4" - 6" of cake I use bubble tea straws and foam core.