[@BrokenPromise]

To me, 'flaws' are just another way of balancing out a character, speaking in strictly competetive terms. Anything that weakens them just shifts them down in tier, which is neither a good or a bad thing, since you can find a willing opponent at almost any point of the power spectrum. As said above, it just depends on how you want to play. If you fancing having a particular trait in your character that happens to put them at a  disadvantage, you can always slightly improve the other aspects of their combat potential and shift them back to where they would be without said trait; and vice versa.

As for your second question... well, duh. If it is relevant, then we will most certainly put it in the character sheet. Weight, height, fitness and bodytype are all common practice to include, as well as sometimes a psychological description and their fighting style of choice. There is this unspoken rule that if your character is an average joe, you don't need to go into great detail about them, save for the actual characteristics that differ from the norm; but i don't think anybody is going to turn down a request to add more information for clarity's sake.