Tue wire you chose is not really intended to make super subohm coils with unless you want 3 strands of wire covering your wick.
A good place to start with 28g is 7 wraps..which is actually 6 wraps with 2 half wraps where the legs extend...expect maybe .4 ish ohm which is plenty nice for flavor and decent vapor.
Depending on what the ohms used will determine what battery you need...If you just dont want to worry much about that then just buy SONY VTC4's and be done with it.
For a build in the .4 ohm range Samsung 25R batteries would be safe to use...but keep in mind this is for .4 ohms...you cant go to a .2 ohm and still use them...But you can with the sonys...Hope this helps.