"a) this is an acceptable use of the system"
Yes
"b) is this the right way to go about finding posts that definitely need editing?"
No. You should not go looking for these kinds of edits. If you happen to see them ...
However, you shouldn't see "hello" any more:
See Should 'Hi', 'thanks,' taglines, and salutations be removed from posts?
We now automatically remove salutations from posts as they are
entered.
I got really tired of performing this edit over and over, so anything matching the form of …
^ # begins at start of body
\s* # possible spaces
(
hii?(?![a-z])| # any of these greeting words
hello|
h(e|a)y(?![a-z])|
dear|
greetings|
hai|
guys|
howdy|
h(i|e)ya|
hola
)
.*? # followed by anything, up to...
(
[.,;!-]+ # one or more bits of punctuation
\s* # possible spaces
|
(\r?\n)+ # one or more newlines
)
… is removed automagically at the time of submission to the server.
Removing "fluff" like this is fine, but not on old posts (they get bumped) and on new posts you should also fix everything else that is wrong with the post.