As to the missing story, that one is easy. You started posting before you were 18. Anything posted pre 18 by a user (for old users and very old minors) is deleted when we find it. Definitely not "randomly missing". You initially registered in 2003, several months before your 18th birthday.
You've been in this archive since you were 17. This means you were around for the crash which garbled everything in 2004/2005. That's something that is slowly but surely being repaired.
As to the rich text editor issues you're having, depending on what word programmer software you use, is how you go about posting in the first place. If you were posting html inserts where Word exported the html, many of those stories had issues. This is because Word exports much in the way of extra unnecessary garbage code. To fix those, you open the chapter and resave. That fixes it.
The wall of text thing often happens when a user goes in to a chapter, where they had originally input the data from Works, and with Wordpad when the rich text editor was first installed. The rte simply doesn't parse Works formatting as it is proprietary. The Wordpad issue was fixed, so anything added from it now will not "wall of text", but you WILL have to go through and apply text format. Several versions back did support Works, but as it's been end of life for quite a few years, it appears it no longer does. (Still trying to find a workaround for that though).
All of this information, whether changes that are being made to old code, how to fix things if there are issues, and etc; are all posted. Changes are posted long before they even take affect to give users a heads up. This has all been covered in the news postings.