Add features to an existing app developed using Phonegap

We need to add and edit some features to our existing app Service Time. Please check below apps first to have an idea of the app. And below is the features need to be completed. Android Link: [login to view URL] iOS Link: [login to view URL] Service Time App Modifications: - when user start the App for first time, select the language page should show first. To allow the user to show which language he need. - Email should be removed from all registrations (of all types of users - mechanic + Trolly guy + normal user) and replace that with [mobile number]. So, Login page should be through (mobile number) not email. - After user enter their Mobile number, a verification code should be sent by SMS to their mobiles (SMS integration should be done) client will pay separately for the bulk of SMS's. - At registration, Mechanic can specify the list of cars types he can fix (he can choose more than one) no need to tell the (car model). Also, remove from [normal user] registration, the type of car & car model. - If any user logged in, then close the App, at any time the user start the App again, it should not ask him to login again unless he sign-out from the settings. - Add a sign-out button in settings inside the App (make it the last button down). - Add (terms & conditions) article page in the setting , above the sign-out button. - Add a mobile number in Contact Us .. in the settings of the App. 056 233 0130 - Mechanic & Trolly Guy , while registration must be able to upload two pictures (profile picture) & (ID copy). - After registration of Mechanic or Trolly Car, it should be sent to Admin for Approval. I will take care of admin section. You will just add it to database. - Admin must be able to [approve or disapprove] the Mechanic or Trolly Car before showing them to the App. - If normal user click on the Mechanic or Trolly Car to see his information, he should not see his mobile number till the request is sent to (Mechanic or Trolly Car) and it is accepted. - While Trolly Guy register, he has to select the type of Trolly he has (look at that in Morni & Droop apps) - If normal user, click on (request a mechanic), the a page should be displayed with Car Brands logos to select his type of car. Then, list of mechanic if will near by will be displayed based on nearest mechanic. - If normal user choose, request a Trolly , then he must specify the type of Trolly he needs. Then, list of Trollies near by will show to him. - There should be a price for requesting Trolly or Mechanic: In city: SR30 Out city: SR50 I am not sure how this will happen. You suggest me easiest way, Is it will be buying credit using in app purchases or it will be easier using paypal?