Did you disable the nodebb-plugin-markdown? This one is responsible for most text parsing including quotes (see this page for syntax).
No. Its enabled.
Recently, when I try to permanently delete a topic, I get the following message:
And the forum crashes and needs to be restarted.
I use a remote mongo database, and I have the option to run commands on it using Robomongo.
What plugins do you have? Try disabling all plugins.