My suggestion would be to read up on the capabilities of MongoDB / CouchDB once. May be take a small programming example in the language of your choice wouldn't hurt. It will take half a day for each ("read up" also means look at the typical questions on stackoverflow, read their blogs, and articles on comparison of their usages and performances -- without all this, your "read up" isn't complete).

Secondly, read up on Redis and Memcache, and include one of these in your stack (I personally stick with Redis, but decide on your own).

If you can spend some more time in your "planning", I would suggest looking at Heroku for deploying your app. If you haven't used a PaaS in the past, this _may_ change your entire outlook on how you plan your app and its resources.

Hope this helps.