Can they be spread?
No, not really.
How common are genital warts to form on the head of the penis?
Not common--usually they're on the shaft. It doesn't sound like a wart anyway.
How would pores on your penis head become clogged if this is in fact what it is?
Don't know, but it's pretty common.
Why would a small bump form on your penis head?
Friction, perhaps. Doesn't matter much.
What is the best treatment assuming it is not a wart?
Nothing.
If the bump persists, please show it to a doctor.
Best.
Dr. Rockoff
--Dave.