Mr. Carter

Tha Carter III Lil Wayne
"I got the floor" is a way of saying he has everyone's attention (the way a public speaker has "the floor" when addressing an audience). But he wants to do better than that; Lil' Wayne wants to be on top (on the "roof") of everything.
Oslo15
Soo woo & da-da-doe are terms that the "Bloods" gang uses to say "Hello" or "Hi" to another Blood member
brandeezy
Sprung in this case means being enthralled by a member of the opposite sex and under their spell or control. The idea that the season "Spring" is jealous of the fact lil Wayne has never succumbed to this is proposed for comedic purpose.
N.Evildoer
The character Beetlejuice in the movie of the same name appears as a fly in one scene. If you say his name 3 times, he can enter the real world from the spirit realm. Lil Wayne is saying he's flyer (cooler) than an actual fly. Impressive.
bill