Ok, so today my advertisements got rejected at three more wordpress blogs because my plugin is not GPL. Another site refused a WordPress article I wrote because it mentions my plugin.

So I got thinking that since I want to make more money with my plugin, I am forced to make it GPL, which I suppose is kind of ironic.

But I have some questions:

Does this mean I can no longer sell the cheaper single site license?

If I make this version GPL will I ever with future releases have the option of going back to a commercial license?

Does GPL allow for dual licensing so that my customers can choose their own license?

If I retain trademarks on my logo and name, does that conflict with making the plugin 100% GPL if those are included with the package?