Would like to edit, copy, paste, create PDF on my Mac - How and what with?

I work with macs (apple computer). I receive quotes and estimates in PDF form. I can open them and print them.

I would like to be able to do the following with my PDF files: edit, copy, paste, also create PDF - most important be able to make changes to the PDF files people send me! What software and version do I need to purchase????? Is there a way to change the PDF files into wither iWork Pages or iWork Numbers???

Thank you.Would like to edit, copy, paste, create PDF on my Mac - How and what with?
you convert pdf doc to word.do wat ever you want and convert again.you can covert by using software.