Hi
You pretty much hit that on the head.
Powerpoint cannot edit PDFs. You can cut and paste screen elements but it hardly keeps any formatting so is not worth it.
Standard will not give you full editability as you will need Pro for touching up (moving deleting etc.) objects. and all edits are fairly rudimentary in comparison to what you are used to with powerpoint and Word etc.
As for changing the particular PDF you mention, if Acrobat still does not permit it, then you have either as you mentioned a protected file and changes are not permitted or the file is a scanned document with all content being in image format so this would need converting to PDF editable content using the OCR function in Pro.
Sounds like you will need to invest in the full pro version to give your client what they want. There is a trial on Adobe available for download.
http://www.adobe.com/products/acrobatpro/tryout.html?promoid=DTELNhth
capt.