Carter II

Tha Carter II Lil Wayne
In this line, Wayne is just saying that he has a lot of problems & he addresses them, like P.O. boxes instead of ignoring them; because P.O. boxes have adresses. Its really simple.
Even though im rich(wealthy) still in touch with the streets (block shit) refers to neighborhood block he grew up on
i will shoot you many times and make you bleed so much that you will be covered in blood from your head to your feet. your socks will be so saturated with blood from your injuries that they will drip.
Wayne is saying that he has returned to the rap game by using this simile. Considering that the hook on a bra (brassiere) is located on the back of an individual. A Play on the word "back".
Wayne is saying that it is useless to shoot (Throw Pebbles) at bullet proof glass, because they will not affect it. This is a simile for how one should stop doing something that does not allow for advancement.
It is better to get small, gradual amounts of money than to get no money at all
Maybe even saying that when trying to deal with one or some, its like looking into a Post Office but you cant remember your Box number.
Possibly that this person has a large number of things on his mind
you should be so aware of cameras or people trying to take your picture, that people might think you have a phobia or fear of photos. this is because the fewer photos of you that are out there, the less likely the police can track you down.
if the money you have was obtained as a result of a caper (robbing someone, perhaps), you should spend it as soon as possible so if you're caught you don't have the money and therefore can't be linked to the crime