Samsung Moment :: CANNOT Change Email Address

I have spent hours and hours on the forum and on my phone trying to figure out how to set up email so it works the way I need to on the phone:
- I CANNOT change my email address
- Download my emails from comcast to the phone and leave them on the server so I can download them to my computer (I set my email client to remove emails from server at different intervals as needed)
- DELETE mails on the phone BOTH in the Inbox and in the Trash on the phone (without deleting them from the comcast server)
- ADD recipients in my replies and preferably myself by default (or possibly as Bcc)
- ADD a several text lines (like a Vcard) automatically at the end of all the emails I send

I tried setting up my comcast mail on the Email app (not GMail or Work mail) - it does neither of the things I need. I tried K-9 and found no way to delete from Trash - which is the main reason I tried it.