If your lever looks like this underneath, then its what I'd call a conventional brake lever (XC pro crom SJS cycles):
The thing with the spring tension is that it really isn't that important to setting the brake up, the springs are only for pulling the pads away from the rim. If they don't retract enough then increase the tension until they do. You've probably found that the barrel adjuster on the brake lever only really changes one arm, the side with the cable clamp. This is normal and this pad will wear faster as this arm will contact the rim first (in my experience). In general, higher tension makes the brake feel better (IMHO).
Not so sure about the cable angle question, it may lower the power a bit but you'll be increaing it by using the cam so swings and roundabouts.
_________________Help identify my frame (DBR?)
Wanted: Black Syncros 27.0 seatpost