I need a word processor that can open/save as .doc and/or .docx.

Use MS Office. If you do not like Word you are basically screwed. You can use Apple Pages but I like MS Word better. For powerpoint use powerpoint or you can use Apple Keynote that is great as long you do not need to share with everyone even it can export into powerpoint.

If for typing you want something free and good, you can use Google Drive, Goggle has many office like applications for free that you can use online, share them and export them at no additional cost.

doc/docx

LibreOffice can read and write almost any document type, incl. docx.
It's free and has more components than Office.
Your choice.
;JOOP!

If you work at a school, you should be able to get ms office very inexpensive or free.

LibreOffice can open .doc and .docx files, and can save in either format. The major problem I have found with that option is that tables tend not to do well in the transition. Workable, but not exact. I keep it because some send files in .odt.

I also have Nisus Writer Pro which can open, but basic format is .rtf.

And because I teach at a seminary I needed some exact formatting for student papers, I purchased MS Office 2011 (at the time it was %99). My least favorite program, but...

If I could get everyone to use it, Mellel is my top choice (language ability [specifically Hebrew and right-left languages], structure, Autotitles, etc.( But I realize it is not practical. I can dream can’t I?