#1 Ive noticed that you been posting a lot of advance guest questions and I would first off suggest that you work with a certified partner. Also a lot of the answers to the things you are looking at are in the help section of your CPPM server.
You enable password reset in the selfservice portal in the guest page you set. The issue that you will run into is that CPPM requires the guest user to login to the self service portal at least once and set a secret question and answer.
This is done for a very good reason. If you allow the guest to just enter their email and hit submit then someone can get another users email address and just keep hitting submit and send a bunch of emails to that user.
You could enable the secret question and answer in the form they fill out and get the account but otherwise they will have to log into the self service portal.
If you want to add the reset function to your login page all you have to do is add the link from the self service portal to your login page.