For the first two questions:
You can open the list box's properties and specify the users' names in the Display column of each value and their e-mail address in the Value column. Then just set the To: field in your data connection to be the field to which the listbox is bound.
You can combine plain text with field values by using the XPath concat() function:
concat("This is the value of field 1: ", /my:myFields/my:field1)