Should I wireframe the app I want developed first ? Also if its its rendered into a mockup would the mockup be sort of the final design that the back end developer works with to make functional ...
Having a general idea, and being able to show that idea to whomever is developing the app for you is a good thing. However, relying entirely on wireframes or Photoshop to deliver a design-outline is bad practice, and should be avoided, especially if you're targeting android-devices, or desktops for that matter. Reason for that being that you have next-to-no control over what the user sees when the user opens the app - hence the app needs to be flexible, able to shift things around if need be, so that users with different size screens and resolutions gets an equally satisfactory experience. Hence, having a mock-up is usually good practice, especially when you're working with other people, just make sure it's understood that it's just a guideline, not a final design. There should always be room for improvement and changes.
A developer or designer won't work without you provide them wireframe of your app. So you have to design your mock up first. If you add few more screens at the end developer will going to charge you extra. So provide him your final wireframe