I've made an edit to (the title of) a question, but the 'your edit has been saved for review'-notification doesn't show anymore. Does that mean my edit has been rejected? And: do I get a notification when my edit is rejected?
You're not notified when your edits are accepted or rejected. Since you still get +2 reputation for every accepted edit, you'll see them in the Reputation tab of your profile. Otherwise, you can go to the list of edit suggestions in your profile, by clicking that link, or finding it under the Activity tab.
I presume this was the edit at issue. It was rejected, as you can see by viewing it. But the "your edit has been saved for review" banner disappearing does not always mean your edit was rejected. It could, of course, mean your edit was accepted.
If you don't see the changes from your edit and you don't see that banner, your edit still might sometimes have been accepted, but then subsequently changed so that your changes no longer appear (or no longer appear the way you expect them to).
By the way, this is outside the scope of this specific meta question, but I recommend that you post a new meta question to ask about why that edit was rejected. Given the edit reason you specified--that the question and its answers are not "online" specific so the word "online" shouldn't be in the title--I think the impact of your edit is not minor. (This means your edit isn't minor. Similarly, an edit that changes a large number of things but where the value of the changes is still negligible even when taken together would be considered too minor.) I would have approved that particular edit, and I'm only refraining from making it myself to avoid an edit war--if there's controversy over whether or not this edit should be made, it's best that it be discussed first. I'm not an authority on what's appropriate as an edit, but if you post on meta about this and wish to do so, feel free to quote what I've said here.