Fan positioning

Whoops. I think we thought you did.

You don't need fans at every fan position. What are you cooling?
I'd add one front fan down low and test your system temps. That might be all you need.
Yes. That's my suggestion. Nice smooth flow in and out.

Although you can test with on the side and in the front.
If you can notice an overall difference in temps - go with the one that's lowest.
Great article on fan placement and the effect on cooling:

With 2 fans, I would place one on the side as intake (directly over the GPU) and one at the rear as an exhaust. 3 fans: add one on the bottom as intake. 4 fans: add one in the front as an intake.

2-3 fans should be able to provide sufficient cooling without becoming overly long as you're using good quality fans with good CFM at lower fan speeds.