it sounds like you have a bunch of different uses in mind for this bike. i agree that the surly is a better choice than the poprad, but after owning a couple treks, i am not the biggest fan of bontrager, so i guess i am biased.
if you go with the surly frameset, you will get the surly steel fork, which is durable and quite nice. personally, i would just stick with that. again, i'd stay away from bontrager wheels and go with the mavics. a good set of wheels is a good investment, especially if you are going to be off-roading.
the surly geometry is more "relaxed" than the poprad, but i dont think that will be a problem for you....although, with aero bars it might be a bit weird. typically you would size a cross bike a little smaller than a road bike or a time trial bike. this means that on a cross bike the top tube would be a bit shorter, and you'd likely have a more upright riding position -- perhaps even with an angled stem. this makes for better/easier/safer handling while racing or offroading. so...thats why i'm saying it might be weird with aero bars. but this all depends on which framesize you go with. if you size your cross bike to fit more like a road bike, you'd be all set.
keep the seatpost straight. trying to fudge the geometry with a seatpost is almost never a good idea.
as for components, this is a matter of preference, but you should be able to run FSA cranks with shimano gearing without a problem. if you can, i would stay away from ISIS as they tend to get worn easily, and the REALLY good ISIS bottom brackets that can actually withstand abuse are quite expensive.
if you like steel, another decent option for you might be the on-one il pompino.
you can get this frame with single speed dropouts if you want, or geared. also, you can get a carbon fork that goes with the frame...which might be nice for long road rides, but prolly not the best for beating it up in the mtns.