Hey Hunzun,
Additional side panels are available for sale, but availability will depend on where you are located. Let us know where you're located and we'll point you in the right direction.
For the cables, I routed most of them underneath the GPU and to the side of the PSU. There's not a whole lot of room, but there is some which would help free up some of the clutter in the front. You really have to bend the cables and tie them down so they stay in place. If you shoot over a picture of the left side of the case with the panel off, then we can get a better look of the spacing.
For the CPU cooler, where you thinking of going air or liquid?