How does the violin strings' gauge affect the instrument's functionality

Question

There are several gauges in violin string, heavy, medium, thin etc.

I know the heavier the strings the louder the tone, but

1. Does it affect the richness (complexity of overtones etc.) of the tone?
2. Is it drastically harder to play?
3. Can it be harmful for my fingers or compromise the sound using a set of heavy if my violin is balanced with 4 medium strings?
4. Do the heavy strings have a longer durability and chance is they last longer?

Regarding the tension on the instrument fingerboard or neck, there is already a nice answer here.

Answer 1

The answer to this question is related / depends on each instrument/player.

One thing you didn't mention and is important is that heavier strings might make more tension and stress on the violins neck/fingerboard.

Trying to address your questions:

1. Yes. But this change is bigger between different brands than different gauge on same brand.
2. Depends. If you have a very high bridge it might be enough for you to notice in your muscles.
3. Depends, not yes/no answer here also. If your bridge is high you fingers will feel it. If the violin has a light neck (not much wood thickness) it might harm the violin.
4. Don't know. I change my strings when the color of the sound died. This is always before their mechanical death/rupture date.

Take your violin to a luthier and check with him. Ask about the tension the strings will put in the violin (neck, fingerboard and tailpiece) and the bridge height.

Answer 2

I'm going with my standard "de gustibus non disputandum" here. Yes, heavier gauge may lead to some finger stress, but proper technique will obviate that concern. Try different strings and see which ones respond most easily to your personal bowing speed & pressure. See if you can hear a difference in the sound – and have an observer listen as well, since the sound you hear as the performer is often different from other listeners.

I remember an interview with Dave Brubeck's group once, in which one of the players noted that Paul Desmond's sound was always about the same (i.e., great), but they could tell when he'd gotten a good reed because he played more easily, with less effort. The same can be said for strings and instrument quality: the right tools allow you to produce with less strain.