Choose the caption bubble to begin. If you want to upload a custom bubble or alternative image then submit the caption first, then edit the comment and attach a "Place img". Once the image is approved you can use it by editing the caption again.
Not really. There is an option with in MAC OS X that can do this sort of stuff on the fly when viewing images. Also very easy to do in photoshop as well.
Damn, not so many entries. Wish i put some more effort into it now and posted some more.