Why put code in bio?

Yes you can send gifts to anyone on your list you just can't trade unless they are close

Yes, u can send a gift to anyone. There is a cap (I didnt count but I would estimate 30 per day).

Reasons to do it:
+ the bonus for Raids counts for the best buddy around. Which basically means: It's enough to be friend with this freak who is there for every raid --> so u dont "waste" any space at all by adding random people
+ 200 friends is a lot. Be honest: U dont have that ;-)
+ Every friend means a higher chance of reaching the cap --> more items
+After 1-2weeks, when gifts arent "new" and "special" anymore u will struggle to reach the cap.

My experiance:
I posted my ID in a thread here. Have 64 friends now. Guess about 10 are people I know. Reached the cap.I got about 20 max revives, 80 ultra balls and 120 pinaps.
So yeah its usefull. The gifts are probably more than a rural player could collect if he played 24hours in his small village.

more usefull than Facebook friends

Yes, I've been trading gifts with my cousin 12 time zones away (opposite side of the planet).