Do challenges provide any rewards?

Question

At the beginning of a mission, one is presented with a set of challenges which may be completed. Aside from the satisfaction, does completing them provide any tangible benefit?

Answer 1

As RSoha mentioned, many of the challenges are linked to achievements (you could say all since there is an achievement to do all the challenges).

In-game, every challenge completed during a mission gives a 5% score bonus, allowing easier access to a higher rating.

Answer 2

There are achievements that are linked to the challenges. I have gained an achievement for completing 50 challenges and think there's another achievement for completing 100 challenges and so on.

As for an in-game reward, I'm not sure if this is completely correct, however, I've noticed a few more items pop up for free on my contracts multi-player loadout but something else could have triggered this.