An NVR is more stable...but your options are more limited...an NVR is plug and play and much more stable...just depends on how much you want to play with it..if you want to set it and forget it got with an NVR...if you are someone who likes things a particular way i would use software NVR...btw if you only need recordings for 5 days xprotect go is something you may want to look at...the free version allows 5 days of recordings...it uses in camera motion detection.
As far as
blue iris controls What type? I believe the only ones that work are the PTZ...not brightness/contrast etc...
When comparing hikvision and dahua note that when placed in 2mp mode the hikvision will give you a wider angle of view (horizontal) than in 3mp..in fact i run them in 2mp for that reason...by way of example...in terms horizontal field of view, a 4mm hikvision bullet is about the same as a 2.8mm dahua turret camera. For offices and smaller rooms that you want to cover i would go with the hik 2532 mini dome in 2.8mm....nice coverage...