I always use the right-click in the top window bar and select the "window" option there and then the "resize window" but I agree it's a PITA and puts one off E23 after a while. Browser pop-ups generally wont have borders provided so that will remain a "problem" there.
No, you're stuck with what E23 has on offer, for now ... unless you want to alter the .edj for the theme and add/replace it there yourself.
- There is a thread (sort of) on theming E23 which might (eventually) be open for requests.
Having fun with themes
Of course you're free to not use (or put it elsewhere) "ibar" and startup "cairo-dock" if you want to. 
The best way is to import the image "again" and provide a different name. The importer will create the required .edj in that case.
