FYI: if you add a 2nd line after a paragraph, it makes a new paragraph on reddit. No problems with what you've written, just thought it might help you.
1) So if someone was interested in working as an extra, they have no agent, no representation, just a few photos, how should they go looking to get considered? call the production company? show up at the office? send a letter? is there a specific title they should be asking for when trying to contact? Once they make that contact, is it just a matter of "Hi there. My name is _____ and I'm a local independent actor and was looking for where I could submit some information to get considered for ____"? or is there a better way to connect?
Should one have a "private line" or backup phone to be called at, does that look more professional, or is it fine to just have your regular personal voicemail? same with email - is yahoo / gmail / hotmail ok, or should they have a professional domain, etc. done up?
Once on the set - is it a good place to network with other people in similar roles, or should one just kind of keep to themselves?
What's the best way to do a good job and get invited back for further work? (other than the obvious and what you've already mentioned)
2) What do you personally think makes the difference between a good actor and a great actor? What do you personally think makes a good first impression?
3) By "enlightened about some of my short-comings by some of the parts that I've played" do you mean personal short-comings or professional ones? In what areas have you learned the most?
4) Do you get paid for auditions? or at least do they cover the travel costs for getting to the audition if it's a long distance? That's a lot of distance...
5) Thank you for the ballpark information. I've always wondered what someone delivering a few lines on a sitcom makes. What about the more regular characters? that ones that maybe deliver 5-10 lines in maybe 4 episodes of a 20 episode season?
6) If you're into marathons and travel, I met this guy a short while ago - he's an interesting fellow - if you're into running you might find him interesting. Ran 250 marathons in a year.
http://www.marathonquest250.com/
Thank you again for your replies - I also have a few colleagues who are looking to pick up some work like this on the side (and maybe make a career of it) that will be happy to read what you have written.