Model 903s, from my experience having owned several, have a nice smooth trigger pull.  I would suspect that yours may be clogged with hardened grease, many are - try spraying it out with carb cleaner or equivalent, then lightly relubing with a light gun oil.  As to the values of the sight adjustment screws - values will vary with distance shot and ammo used - you need to regulate it to your chosen type of ammo.  My best guess would be one click per 1/2 inch at 50 yards for elevation and the windage adjustment is undefined - you loosen one side, slide the sight blade and tighten the other.  This model, again from my experience, has some very good to excellent accuracy potential.  Good luck.