Have you received an e-mails offering compensation or referring you to a website for the delays?

The bag delay -- as mentioned there is a standard $1,500 offered for more than 3-day delay plus reasonable expenses in the meantime. See details in Consolidated UA Lost/Delayed Baggage Issues especially the wiki/summary

The voluntary (but realistically "involuntary") downgrade -- write http://www.united.com/refunds for the fare difference. And a separate email for the inconvenience. Don't call it basic economy as that term has a specific meaning, regular economy is a good term to use.

The lack of special order meals should be a separate request to www.united.com/unitedcares

Sorry to hear of your troubles, I think you had more issues in this trips than I have had in a lifetime of flying. Hopefully, that will mean a better future for you.