The reason why we choose a small number of days to download your content is simply because when you used the app, the photos remained on your phone.
We're monitoring who's downloading their content and who's not. If we see that there are a large number of users who still haven't downloaded their content, we'll adjust that date.
MySQL is what we started with, as time has gone by, we've migrated more and more data to other data stores.
Redis and mongo solve two different problems for us. Redis is great for the social graph, which is how we've started experimenting with it, whereas mongo is best for just about everything else that doesn't hold the data in MySQL.
Thanks. Our complete stack is quite complicated, but a quick run down of what we're using: mysql, memcached, mongodb, gearman, nodejs, redis and puppet. (Node and redis are not in production currently.) The main language we use is php. I know, ugh, from all of you ruby and python guys, but good clean php is as good as any of the other language.
Yes, we have plans to expand the user demographic. Our product roadmap should help with this. We're just too constrained right now with engineering resources.
We're hiring iOS, android, web frontend and backend engineers. Shoot me an email (ryan @dailybooth) if interested.
It's probably also worth mentioning that we currently only have 2 engineers. So if you have interest in working on the full stack and having your code pushed to production where you can actually see users get excited over what you build, then make sure you get in touch. The thing that will hold us back the most is engineering resources (which we're actively attempting to fix).
We're monitoring who's downloading their content and who's not. If we see that there are a large number of users who still haven't downloaded their content, we'll adjust that date.