My question is simply; are the Remove Procedure Calls executed on clients in the same order they are called in the server? I tried to get it to execute out of order by using a huge amount of function calls via the in-editor multiplayer, and there they always execute in the order they are called. But this might just be because it is local?
well, UE is single threaded in that sense. That is why you get the same order and there are no delays (local). BUT, what you can do is fake lag per client (Finding Network-based Exploits - Unreal Engine) and see the order.