(Sort of) New User Questions

After many (many!) years of using v2, I finally ungraded to v10. Needless to say, there have been a few changes, most of which I have figured out. Here are a couple with which I need help.
 
1- I'm  a plain-text person, not HTML. I will use it for email when absolutely necessary. I want my new messages -and- my replies to be in plain-text. Where and what are the proper settings to make this the default no matter what format the reply is?
 
2- Perhaps related to #1, when I add an attachment to a new message or a reply, it becomes part of the body of the message. In v2 I was to have attachments as icons in a pane to the left of the message editor. Again, how can I make this the default?
 
3- In regards to this mailing list (TBUDL) how can I change my email address? I signed up with one address, but am now needing to change to another.
 
Thanks.

________________________________________________
Current version is 9.1.18 | 'Using TBUDL' information:
http://www.silverstones.com/thebat/TBUDLInfo.html