Thats true but for each clone his strength drops as a result of equalising their chakra so its still even in that respect but I would be amazed if he even needed clone's lol. But as I said earlier he won't pass the first round.
One clone can take out 3rd Raikage, yes it was with knowledge, but he still took out the 3rd Raikage with a clone.
Honestly, one clone is enough to take out a chunin.
And although I can't find the exact number of people who took the Chunin exams, I'm pretty sure it was less than 1000. I just said 1000 because I knew it wouldn't be higher than that.
Naruto will pass the first round. We don't even know what it is, I think the chunin exams change every time they do it because I remember Kakashi doing an exam which was different to the Chunin exam we saw.