You appear to be asking for more than the PDF format can give you. Adobe Acrobat X Pro is not intended to edit PDF files in the same sense that you can edit Word documents. It is intended for mark-ups, annotations, forms creation, signing, and such like. Actually, the mission-critical function of Acrobat Pro is the creation of PDFs using the Distiller application. Immediately above your post is Natobasso's post in which he recommends SmileOnMyMac's PDFpen. At $59.95 for the regular version and $99.95 for PDFpenPro, SmileOnMyMac's appears to be fairly well align with Adobe's educational pricing.I've had zero problems with the Adobe Acrobat Pro X, It does all that you're asking. but it is expensive,
Skim and Preview are good, you can highlight the text or annotate your PDF with them, but they can only deal with basic editing. Once saved, the PDF will become un-editable again.