One of the beautiful aspects of a SA/DA is you can half the trigger pull by cocking it if you desire.
I generally try to steer folks away from snubbies for their first gun. They are hard guns to learn to shoot well, or at least harder than a full sized gun. Short sight radius, marginal sights, heavy trigger, long trigger reset, etc. If you're set on an SP101, the 3" will be a bit easier to shoot.
Something like the Shield is easier to learn to shoot better faster, is lighter, and is approximately the same size. The cost is about the same, you get more capacity, you get a longer sight radius, you get usable sights, you get a lighter trigger, etc.
If possible, go to a range (or a well stocked friend) and shoot a few different guns to see what fits your hand, what trigger system you like, and go from there.
2. Stay away from the polymer/titanium snubbies. They may ride better, but physics dictates that they will be more punishing to fire which could lead you to hesitate when you shouldn't.