Yes, you'd put the slot fan over one of the pci x1. It doesn't actually fit into the slot, it just sits above it so you can place it anywhere there is an open bay in the back panel.
My personal rule...when I buy fans w/sleeve instead of bearing I pay top dollar for the higher quality fans. I don't think bearing is all that much better but the tolerances are more precise usually resulting in a smoother running fan and at high rpms noticeably quieter then sleeve fans.
You put in front of the gpu fan so it works with it to pull hot air before it hits the gpu fan. Gotta watch the rpm settings on them both because the can create this dead zone between the fans that's definitely audible.
Yes, you'd put the slot fan over one of the pci x1. It doesn't actually fit into the slot, it just sits above it so you can place it anywhere there is an open bay in the back panel.