I once took the Veritas free test and scored 700. The very next day, I took GMATprep 1 and had the exact same score. There are no reports of Veritas being too hard, as far as I can tell... Maybe you were just having a bad day...

Practice CATs are supposed to mimic test day conditions, so I'm not sure if rushing through is the best approach. Maybe you'll get so used to this that you'll rush through the real thing too and lose valuable points, with the only "upside" that you're going home earlier...

Picking the first answer that seems correct does make logical sense up to a point, with the extra time on your hands a valuable asset. However, in my experience, GMAT questions are written in such a way that the wrong answer choices are the exact wrong ones that you're likely to get. If the answer is 3, they probably won't post an option of 3000, for instance, but use 2, 4 or 5, which are pretty close. Remember, calculations CAN go wrong!

IMHO: save your practice tests. Doing one practice test per day is not your best bet for improvement; actually, I think you just might be wasting valuable resources. Think of it this way: yes, you review the questions you got wrong, and say you got 10 verbal wrong, with 3 CR, 4 SC and 3 RC. These wrong questions are spread across a wide spectrum of topics/skills tested, so you're only working through a small bit for each section at a time. However, if you work on CR for a day on say Weaken questions, that type is much more likely to stick to your head. Same goes for quant: you'll be reviewing number properties, statistics and geometry in the same go. Working on so many at a time will not help you understand the underlying principles! That's what books are for (i.e. Kaplan, MGMAT) and NOT practice tests.