OT - How to use the mailing list?

I've always tried to get help from either #netbsd@freenode or by googling. 
There are time when both method are inadequate.

I've read but never tried posting here before. Read some guides to mailing 
list but still couldn't understand the concept behind it.

My doubts are:

1. Must I subscribe to a mailing list to participate?
2. Who do I reply to when I get a reply? The mailing list, the person who 
replied, or both?
3. Now I have noticed that people replies to only the sender's email 
address but how does the reply get listed on the archive when the reply 
was directed to the sender's email?

I haven't subscribe to any mailing list yet.