Hi there,
as to Part 1, this is not a big deal, since all the variables needed are apparently available in the script, and it is all just a matter of adding them to the e-mail and polishing up the form of the e-mail.
Part 2: The only potential problem I can see is when the user enters an invalid address (otherwise, the API provided by Google is sufficient). In such case, a small alert window could pop up to let them know that an address could not be recognised. Optionally, after such an alert, an option could become available in the form, that would allow user to enter the distance manually (or, of course, let them try changing the addresses provided).
Feel free to let me know if you have any comments, further suggestions, etc.
Sam