i did something similar to 1. in my software sms2mail
you need to open a connector on the sms-port and you'll get the messages exclusively.
you can create a new message object in the inbox and play an alert maybe, not sure about this.
regarding 2: why whould anybody want to send a mail2sms message to a BB? Blackberries can receive mails, thats their reason to exist...
As your BB does not have a public IP you won't be able to access specific ports without using the push service of the BES.