Now Adobe Acrobat does allow you to apply numerous modifications to your existing PDF documents (like editing text, changing font attributes, inserting images and more) but, as you know, Acrobat is an extremely expensive software.
If you are on a budget and wish to edit PDF documents without Acrobat, the easiest option is to make edits in the original document itself and recreate the PDF using Google Docs or any of the free PDF writers.
When that is is not an option because you don't have the PDF source files, the PDFill PDF Editor (link) can help you manipulate PDF documents though it may work with password protected PDFs.
The PDF Editor is freeware and lets you make basic changes to PDF files - you can reorder the sequence of pages, crop a PDF page, add text information in header and footer, add image stamps or even merge multiple PDFs into one.
PDFill PDF editor is still limited like it won't let you edit that phone number or address in the PDF - another option is to download a trial version of Adobe Acrobat Professional - it works like a charm for 30 days.
Related: Extract Text from PDF with Gmail