Total control of your posts layout: adds code (Google AdSense, ...) before, after and in the middle of a post or anywhere with a block short tag.
I'm not a programmer, I cannot modify my theme so:
The answer to all those questions (and many others) is with Post Layout.
And when you cange the theme... all continues to work.
The plugin is VERY useful to everyone need to add AdSense or other advertising code in the post body (before, after or in the middle of them). The plugin injects the code without modify the theme used and is "theme independent", so you can change the theme and the custom code you added won't stop to display.
The plugin can inject such code in the comment form, too, and after the last comment: those two positions are useful for blogs with a lot of comments, so there will be ads even in the bottom of a long page.