The biggest question which got me stuck for more than 10 days was what sdk should be kept as the minimum targeted SDK, the basic difference between the different SDKs is the new functionalities they support which are not backward compatible without the usage of a support library or SDK. Definitely using a support library is extra work and when you are doing it solo avoid the extra work as much as possible but without any compromise with the quality of the final product. Moving on, to see which SDK, the most number of phones are running now you can visit the Android Dashboard @ https://developer.android.com/about/dashboards/index.html

It lists down everything clearly, the rough stats about the versions of android most phones are running currently, about the screen resolutions and also about the OpenGL support for when you are planning to develop graphics centered game or even app for that matter.