Alright, I've read a few of your threads, and I have one thing to say. It's going to be the best advice you have ever gotten.
Stop worrying so much about the little stuff. You will never get famous if you don't first dedicate yourself to the craft.
Don't worry about your age, don't worry if you write first, or find a beat first, just calm the fuck down and record.
Rap is suppose to be fun, you are seriously over thinking everything.
& no, your not going to be famous in four years, you will never be famous. The odds are stacked against you, so just try to have fun with rap.