Ok, For point 1 :
Well As i thinks your application Target mode is by default selected as manual.
Select Run Tab in eclipse->Select Run Configurations -> In that select Target Tab ->Select Automatic instead of manual Click on Apply button and now hit run.
Now your app doesn't prompt for a device.
For Point 2:
appcompat_v7 is a support library in android, so if you already have this library some where in the workspace then it would not be created each time.
for more see here .
For point 3 :
While creating the new project set the minimum sdk version to 11 in fourth one column from top.
see screen shot for help: (Note this pic only for demo, where to set minimum sdk version)