Add two features to my php form

I have a html/php form already created that will serve as a registration form for a dance studio. The form currently is working and already does the following: [login to view URL] user info through input fields [login to view URL] a selection of classes the user is registering for [login to view URL] the data to a csv file on the Web server [login to view URL] a detailed confirmation email to the user listing the registrants name and a list of classes for which they registered. [login to view URL] an email to the form owner with all the registration info except the credit card number (the owner then logs onto the password protected directory and gets the cc number from the csv file) I need the following additional functionality added to this php form: 1. Total calculation with discounts applied Once the user has selected their classes, I need the form to calculate the total fee for all the classes selected with the following discounts calculated: 20% discount applied to total if 2 classes are selected 30% discount applied to total if 3 classes are selected 40% discount applied to total if 4 or more classes are selected Preferably, I would like the user to hit a “calculate total” button at the bottom of the form to see the total without changing to a second form page. Although, splitting the form into two pages would be ok if necessary. Please see the attached form . . .I've added the calculate button and indicated where I would like the total to appear. 2. Printable confirmation page listing the same confirmation info the user receives via email (listing the registrants name and a list of classes for which they registered). Thank you for registering <name from form> for the following classes: <class 1> <class 2> <class 3> 3. Make one field the “Release of Liability Disclaimer” Required with a simple method like javascript. I need an expert PHP coder to complete these last three steps. You may use the PHP code I’ve already created, or start from scratch. The sample form and script are attached. Please let me know if you have any questions.