The gamma is purely for personal taste. With pedals that have shorter travel or less resistance, you can work around difficulties with increasing gamma. For example, with my stock G27 pedals I used a gamma of around 1.5-2.0. But once I fitted a GTEye progressive brake spring, I pulled it down to a fully linear setting, as I had the necessary feedback from the pedal to properly manipulate the brake on the lower half of the input. With my current T3PA setup with conical brake mod I actually found anything not linear to be distracting.
Regarding brake bias, it's all about the balance of the car and the characteristics of the track. During braking, you'll have more load on the front tyres, which equals to more grip potential as well. On a track like Monza, or any track where you have low speed turns after a long straight, a more forward bias can help to achieve shorter braking distances. You'll heat up your tyres more though, which will adversely affect your cornering capabilities, and you have to be careful to properly balance the car before turn in, or you'll face a lot of understeer. Put the bias too front and the rear might want to catch on you during braking, or even the fronts can get over their edge of grip and you'll just fly off the track in a straight line.
A general rule is that RWD can appreciate a more forward bias, while FWD more to the rear, due to the driven axle and their overall weight balance characteristics. Moving the bias to the rear can also be better for trail braking. Give it too much though and you'll be struggling with oversteer and longer than optimal braking distances due to the rear end loosing grip or blocking.