There are thousands of posts about apps that need memory in the phone and the issue of Android overall in this area.

In short, it doesn't matter how much space there is on the card. Sorry but all this is too well discussed.

OK, it looks like you are good to go. http://www.gsmarena.com/samsung_galaxy_s_ii_skyrocket_i727-4303.php notes 16GB internal memory so you need about 3GB free there to be sure.

-> You bring up a good point. Should Samsung explain Google's Android OS issues and limitations?
Or do you expect the makers to fix the OS they use?
Dell certainly didn't.
Bob