Edit my existing Android application

I need an expert in android applications to make some changes and gather some information on my current apk. Need to decompile edit and repackage My issues: An Email address is collected within the start of the apk i need to know where this is then stored in the device its lauched upon, the email address is also sent to "Stripe" for processing a payment at subscription stage so it must pull it from whatever the stored location is. Need some minor text changes Need to re-collect tghe email address at payment stage or display the stored email address so information can be edited. The developer must be an expert at android apk's decompiling editing etc, must also have excellent knowledge of GET POST api commands and the STRIPE card processer.