lammert - 10:14 pm on Jan 10, 2012 (gmt 0)
It is no problem if the helo address matches example1.com for emails sent from example2.com. This happens all the time, for example with Google Apps or Microsoft Office 365 sending out emails for all the domains which use their platform.
The same for problem 2. The contents of the PTR doesn't matter, only the existence is important.
To give you an idea, I just checked an email received from the Microsoft Office 365 platform:
A reverse PTR check of the IP address which belongs to the HELO name gives ch1ehsobe001.messaging.microsoft.com So the reverse PTR and HELO address are not matching in this specific case. This is perfectly allowed behavior and you should not worry too much about it.