"BD bikes are fine, just take it into a shop to get properly assembled".
That should also read, just take a ride on one before you buy it. Quite a few people do get the wrong size or wrong suspension and then you have made an expensive mistake by going the BD route. And if you are intermediate rider as you state, you should know the answer or have a good opinion on hardtail vs fs. If still in the dark, ride a buddys (or a loaner from a LBS) fs and then decide. I've seen riders on some nasty, rock strewn, root tangled trails here in N. Cal. on hardtails passing riders on fs bikes. I have also seen a few fixed fork hardtail riders travel where the fs riders tread...pretty cool watching their expert skills. Short answer is either will work and neither one is mandatory.