Hi AJlnmiit,
You pose some good questions. Maybe you're a naturally strong Test Taker, but maybe this practice CAT didn't function correctly. Based on the percentages, I'd be suspicious too, but we don't know for sure either way yet. You might consider taking another CAT (from another source) to see how you score. With that extra data, you'll have a basis for comparison.
When it comes to taking a practice CAT in the future, you're going to want to emphasize the "realism" of the experience. Taking a FULL-length practice CAT, under "test-like" conditions, is really the only way to assess your overall skills and get an approximation for how you might score on the Official GMAT. To that end, don't skip sections (take the Essay and IR sections), don't do anything that would be considered unrealistic (pausing the Test, listening to music, eating/drinking during the Test, etc.) and take the CAT at the same time as your Official GMAT.
GMAT assassins aren't born, they're made,
Rich