When you say the battery draining in a couple of days I presume thats with the car in use if so as said you have a charging problem. Do you see the battery light on the dash when you turn ignition on?

For the brake lights as said will 99.9% be switch (On top of pedal itself)as you have covered the fuse and bulb. Check continuity on the switch.

Roof probably is as you say as there is not enough power.

Martin