Modification to registration page

We have a site where trades and service providers sign up with us. To complete their registration they need to create a paypal subscription. They can decide to either pay monthly, or annually at a reduced rate. see here: [login to view URL] click on either green button. On submission of this form, their information is automatically added to our client database (as an unpaid member at this stage), they are sent an introductory SMS and then transferred to Paypal to create their payment subscription. Once we receive the email from Paypal that this subscription is in place, we change the field in their record to PAID and send them an email thanking them for joining with further info etc. We wish to automate this process and streamline this page as it uses two separate form layouts in i-frames etc - it's all very messy. The work to be done is as follows: 1) remove the i-frame layout by using just one form where they select select their payment method by way of radio buttons - monthly or annually. whichever they select will direct them to the appropriate subscription setup we have within paypal 2) make the first field they need to fill in be their mobile number. once they fill in the 10 digit field it needs to be checked against our database. if their details are already listed, a warning popup appears stating they have already registered with us previously - the information we have on file will now be filled in for you. the form is filled in automatically with the relevant info from the database. 3) their details are added to our database if not already there. We want their details added even if they do not complete the paypal step following as we will approach them later if they do not complete the paypal sign up process. 4) they are directed to the appropriate paypal subscription page - one for monthly, one for annual payments. 4) if they complete the paypal sign up succcessfully they are returned to a page in our website thanking them for joining etc, plus the thank you email and SMS is sent to them 5) the field in the database is changed from UNPAID to PAID. This is our proposed way of doing it - if you have a better suggestion(s) we're happy to hear them. Attached is the html page - [login to view URL] - that i-frames the registration form - [login to view URL]