I've had many posts deleted.
Posts are deleted when they break
forum rules. Stop breaking the rules and you're fine.
Once I reposted a deleted post and the moderator changed the text.
This comment is worthless without a link to the post.
Now with this username there have been no outright deletions, but a moderator combines any two posts into one then sends the message
Stop multiposting.
Mods are not supposed to edit the content of a post, even if it's a sticky. Mod edits should be limited to non-content things like fixing broken bbcode, merging posts, etc., so that nobody ever has reason to complain that a mod "put words in their mouth". Even if a post is violating the rules, and editing out a word/sentence/paragraph would make it no longer in violation of the rules, this kind of content-edit should not be done; the post should just be deleted.