Help me optimize my system

So I do Premiere Pro and After Effects, and I'm trying to figure out what is the best configuration for my Mac Pro 2009.

Here are my ingredients:

256GB SSD 6g
4x1TB HDD 6g
128GB SSD 6g
External HDD RAID 0 eSATA 3g
PCI-e SSD card with eSATA port 6g
nVIDIA GTX 570
nVIDIA GT120

So with that what is the best setup knowing that I would like different disks for OS, Media files, and Cache files.
There are only 4 PCI-e ports on the machine and the internal controller is SATAII so that max speed is 3g, only the PCI-e card can do 6g.
Also the GTX 570 does not have a boot screen so I might want to keep the GT120 in.
I'm open to any proposition of new things to buy in a reasonable price range to make the system better.
Any chance I could edit 4K with a system like that?

 

Ain't nobody got time fo dat?