Billy, it's perfectly normal for your penis (and scrotum) to get darker as you go through puberty. The glans can be red or a dark purple and still be perfectly normal for you. As long as you can retract your foreskin it's not a problem.
In some guys the glans is thicker than the shaft, in others it's the opposite. Both are normal.
It sounds like you have an irritated meatus (opening). Make sure you retract your foreskin and wash underneath it every day. Also, after you pee, take a small piece of toilet paper and blot any remaining urine to dry it. Don't let your foreskin go back over the glans if there's any urine there.
About the dark ridge (it's actually called glans corona), I have same problem, I'm not sure whenever it's something bad... I searched the Internet and I was able to find few posts on forums like this stating that's normal... But I'm not sure. Does it feel different???
And about urethra pain, I think it may be inflammation? It's pretty common thing, but I'm not sure it can give such symptoms as red color.
Also I have no problems pulling my foreskin back beyond the head when my penis is in a flaccid state but it's quite painful (but not impossible) to when it's erect