I am full time developer, working with Java and Android for a few years, already.
I have experience with all of the requested technologies, including JSON, saving data (I usually use data binding), handling application based on user being signed up or not, web services, and MBaaS.
Because of my full time job, I will take a little more time to get the job done than most of bidders.
Since I am new on this site, I suggest I few milestones, so that you can see I am serious and that we both are protected from scams. You are free to suggest changes in milestones.