Demoronizer, tidy, and various other aps have been discussed here.
Scott7477 is just beginning work on a tut on this general topic (and I'm allegedly helping, though in fact, planetscape has -- IMO -- done most of that by pulling together a formidable collection of refs, cites, etc.) while I may be of little value other than word-butchery.
GrandFather has posted
a WYSIWYG editor in CUFP which may be relevant and helpful. I could undoubtedly name many other relevant resources...
BUT...
Were I in your shoes, I would not allow "cut&pasting" of M$word (so-called) .html under any circumstances... for the very good reasons you outline... and
perhaps even more important, would not allow use of any other than a very small subset of html tags for a whole range of taste-, security- and simplicity-reasons and just plain "old-fogey-ism."
On the other hand, the Monastery does provide minimally restrictive methods for a visitor to write some .html. Have you explored those methods?
