#2
Tell them to leave a comment/message with the address. Use a Yahoo mail account and add them all to your contacts I suppose. Then just send it to everyone. I don't know any other way to do this easier, but I'm sure there is one.
#4
my advice would be to use something like google groups

unless you have your own hosting and a knowledge of php which i guess you dont.

google groups is easy to set up anfd lets u sedn out emails to every1 who joins with their email

im guessing it also has widget things u can have up on ur myspace where people can auto opt in by just writing their email in a small box