sig and forum questions?

Hello,
I have a few questions based on the fact i'm new here! i tried the search for these answers and had no luck. I was wondering what the icons on the left side mean when you open a forum like: the white boxes with flames and without etc etc? i was also wondering how some of you have pictures on the top left corner and some on the bottom of your post? I know rather well but the thingy says off when i go to edit? and it says (img) on? all i know is is that how you some of you are doing that? or what is the proper way to add pictures?
Thanks a Bunch !