wp email forwarding how ??

On my site I wish to create a button (already have the code etc), that will require a person who works in a particular field, to see the certain information related to that work but not for all eyes, (ie joe public) by clicking a button and filling out short form asking for position, responsibility and place of work so that we can send out a password to log in for them to see said info.
I know this has been done a zillion times but for me its first time and I would like to get it right.
As I see it the procedure is as follows:

Client sees 2 buttons….1 says “Log In” second says “Request Username & Password”
Client clicks on button 1 (request user name and password to access this page)
Page comes up for entry of info…
Offers box to enter selection of user name and password…
Client clicks ‘send’ *See note 1)
I receive this as an email..
I can then respond to email with and confirming log in details…
Client click on second button “Log In”..
Dialogue box for person to enter User and Password,
Once entered and clicked
Opens page that has info.

Note 1: I read I can use the internal ‘name@wordpress.org’ email system so that my hosting server where WP installation is located will receive the request and notify me by email that a request has been submitted. I can then allow “New User Approve” plug in to allow.
How and where do I store the Log In and Request Username & Password details.
Now its quite clear that I need a page that has the relevant sensitive info on which I have already drafted.
How do I link to that so the client can see page but once finished and logged out the screen return to that Login page.

Now I got this from a great gut at Gravity…

The easiest way I think would be to have them register as WordPress users, since you are asking for a username and password, and will confirm those details for them. If you create WordPress users, then moderate them (approve their membership) you can then hide the second form, the restricted one, on a page the requires a WordPress login. I think that is the easiest way with what is already included in Gravity Forms.

http://wordpress.org/extend/plugins/new-user-approve/

The New User Approve plugin can handle the moderation of the new users, and then Gravity Forms can require that the user be logged in before seeing the form.