Editing PDFs - basic, low cost/free, easy to use app

Hi
Very occasionally I need to edit PDFs. I am looking for a very basic, easy to use (or free) app that let's me simply insert an image (or block of colour and text) into a PDF as you would with Photoshop Express etc. Is there a simple solution for this?
Also I would like to be able to resize all the pages in a multi-page PDF so they are all equal.
Thanks in advance for your advice!

There is no app I know of it does what you described. I don't think you quite get the concept of a PDF -- it's not meant to be changed, that sort of defeats its entire raison d'être.

There are third-party utilities that will let you turn the text back into a word-processing file, or fix typos in a PDF, but nothing like what you're describing.

I second cha-m's comment.

PDFs are Portable Document Files, a digital version of paper, for reading not writing. The text and images will read as laid out but are actually simply positioned all over the digital page in bits and pieces, not neatly breaking where you expect.

Preview.app very cleverly will let you select the text, even if it is in multiple columns and Copy/Paste that elsewhere, but it doesn't always get the formatting or text order correct.