Hi Rich,
Regarding item #3, this is related to the "track e-mail object" question preceding it. To keep the email attachment you need to select to track e-mail object. In the form that comes up when you turn this on, try putting in "currentobject()" without the quotes. This will save the email to the item the rule is running on (project, task, milestone, issues, etc.)
#4 is related to #3, without the item above working #4 won't work either. When this email notification goes out from the system, all the recipient has to do is use "Reply All" and their email will be tracked back into the system. No Interact functionality is even necessary in this case =)
Josh