Here are the answers I found (with some help) to these questions:
(1) The instructions specify to be sure the FTP client is in ASCII mode when uploading. I used the Control Panel File Manager. Is it always in ASCII mode? If not, how would I set it to ASCII mode?
ANSWER: Uploading files via LPCP is in ASCII mode
(2) My initial attempt at configuration was not successful and now I do not get the password page when I put in the URL to get to the configuration page. What does this mean?
ANSWER: Not sure what was happening here but I was able to get to the password page the next time I tried.
(3) The instructions say to set the permissions on the TFmail.pl and TFmail_config.pl (yes, I did rename them) to 755. The Perm's area in the File Manager does not have numeric values. There are settings of r, w, and x (read, write, delete?) for Owner, Group and Public. How do these translate to 755?
ANSWER: I Googled "755 permissions" and found several explanations.
(4) The code in the final configuration box referenced a CSS file called 'nms.css' but I didn't see this file in the zip archive. Do I need this for the configuration/form to work? If so, where would I find it?
ANSWER: Apparently this file either is not needed or is already present somehow. Anyway, the script is working now.
Hope this helps someone else!