DKS...
software defaults are default for a reason...the numbers (which are similar in beersmith to promash, but using pellets as the default) aren't pulled off the top of the programmers head.
Yep gotcha there
The utilisation differences between the hop type are based on various factors, not the least of which is different surface area available to the wort. (think in terms of coffee...coarse grind vs fine grind).
Yep makes sense
I don't see how the AA of the hops would effect the utilisation when comparing hops of the same alpha, but one is pellets (finely chopped, then comacted) to plugs (compacted, then chopped) to flowers (whole, obviously).