Are there any rules about the difficulty level of an approved speedrun?

I'm also wondering if its frowned upon to use the "Special" weapons you get before you even start (the Driller)

@TheDefnOfInsanity Doing a speedrun on a certain difficulty does not apply to the rules unless the mods make a seperate category for that difficulty. (E.g. Far Cry 5 speedrunning has a new game+ run which can only be played on the infamous difficulty). As for “special weapons” and “DLC items” they are strictly prohibited if the rules say they cannot be present or used throughout the run. But as the rules do not state it’s prohibited I assume you can, but be sure to check with a mod just in case. Hope my response helps 👍🏻

Yes you can use DLC items in FC4 Runs. I used Driller for the most part of my segmented run.