Hi, I reviewed a lot of ideas trying to join Wayra, the Telefonica backed accelerator. Everyone thinks his/her idea is great, but only a few are really disruptive and have potential enough to be pushed by the market. Better than starting to build it, try to surf the Internet and look for similar ideas. Understand what's really new to support your idea, the potential risks if you finally build a business over it and try to compare your skills and background with other people building something similar. After that, if you are still convinced it's worthy to make it your live, start looking a tech cofounder that will help you to turn the idea into reality.

You can consider a lot of things and get a lot of advices and recommendations from everyone. All of them are right, but finally you have to make the decision. So, the most important thing is that you should feel comfortable with the final picture.

If you do not know the calculator referred by Heather Wilde, maybe you find useful. I encourage you to try it. It always works for me (http://foundrs.com/)

Better than choose an architecture and try to build the server side of your app, I suggest you to try to find a mate that helps you and was your cofounder. Just you will probably fail in building the app and keeping it working fine in the near future. One-founder teams are very risky for accelerators and VCs. So, you definitely should trust in a co-founder. Read this: http://venturehacks.com/articles/pick-cofounder