what type of fan fits at the bottom of the case and under both the gpu and mobo? I'm thinking of trying to add more fans if possible. I managed to only find one pic displaying this and that was on pcpartpicker.
A slim (14mm) 92 fan. There's basically only one out there, I even believe that Dan designed the new revision for this fan specifically. Don't quote me on that though.
Noctua NF-A9x14
Noctua NF-A9x14 Chromax version
They are the same fan, only the Chromax is an all black version of the original NF-A9x14.
One thing to note though, is that this fan doesn't do all that much really. It can lower temps maybe around 1-5 C at max. Keeping in mind as well, that in this case, which is basically one of the most compact cases on the market, cable management is a nightmare. The lesser cables you have inside of it, the better.
Personally I only have 5 total cables: Front usb cable, fan cable from my AIO and then 3 PSU cables. Which are 1 for the GPU, 1 for the CPU and the last one is the 24 motherboard cable.