No more than 600 words per chapter, for all AN in a chapter, actually. We've actually got an option built in for the new software in development. However, it doesn't want to work with the current software (we tried testing it and are still trying to see if there's a workaround that will work with the much older code).
If you want to discuss your stories, yes, you can do that in the forum, not the review board.
As to the stresses, that has everything to do with age of the current scripts, how they parse the data, how they interpret queries, how queries are structured for it, and load to the database server itself. Seeing as how there are incompatibilities, and in fact drastic changes to the query language itself from when this was written, and the versions it was written in, to now; this is where we run in to many issues with putting new functions in to the old software. With the version gap between languages and software, there have been significant changes in how scripts need to be written, and how things are structured. To the point where if inserting a function in some for instances, written in php3, it may not work in php4 or php5, and often DOESN'T work. That has to do with how the php interpreter itself has changed. Also, inserting a function written in a more current version of the language doesn't always work either, as while the interpreter will use it, there have been many times where we've found it's simply not supportable in the old code itself and causes problems of moderate to often severe variety within the old code itself.