The newest versions of Adobe products are taking advantage of NVidia's CUDA technology, which provides better performance with cards that have a higher number of CUDA cores. They can accelerate more than just rendering. They are now used for the encode process and many of the effects plugins. If he uses complicated effects, then it makes sense to have a high-end GPU to accelerate those effects.
Like I went into on another thread, the 3930K is the CPU to get if you are serious about video encode quality. The best video encodes/transcodes are performed in software on the CPU. The Ivy Bridge CPUs provide great built-in GPU performance for video encoders that support Intel's Quick Sync technology, and you can also get great hardware-accelerated performance from a discrete high-end GPU, but the absolute best quality has always come from a software decoder/encoder running on the CPU. If you have to run the encode on the CPU, then the fastest way to do that is to get the 3930K (unless you want to blow an extra $400 for 100MHz more and get the 3960X).
For the motherboard, get the Asus P9X79 WS. The WS model was specifically built for workstation use and has better support for hardware RAID controllers and LAN cards. This would be the way to go if you want to get that LSI RAID controller. Motherboard RAID support is NOT considered hardware RAID. It has some functions that are handled in the motherboard's chipset, but a lot of the RAID functions are done on the CPU in software. Motherboard RAID is sometimes referred to as "FakeRAID" because of this. If you are only using RAID for the purpose of performance, then you probably don't need a hardware controller. The hardware controllers are most useful when it is important to have some form of redundancy. They are especially handy when it comes to RAIDs 3, 5, and 6, since they require parity calculations in order to provide redundancy, and these calculations can be done on the controller card instead of the CPU. Hardware RAID controllers are also chosen because they can provide battery-backed write cache, which allows the RAM on the controller to save up a bit of data to write to the array and dump it to disk when it is most convenient for performance-related purposes. Without the battery-backed cache, you can lose data if the computer loses power. If the RAID controller doesn't have any RAM to use for caching purposes, then you are losing one of the greatest benefits of modern RAID controllers. Unfortunately, cards with battery-backed write cache are very expensive.
Adobe products get their best performance boost from better RAM. I would suggest that you set up the full quad-channel experience available with an X79 build! Faster RAM also helps, so start with 1600MHz, and consider jumping up to 1866MHz. Go with a 16GB (4 x 4GB) kits at least if you are using Premier Pro. I stuffed 32GB of 1866MHz Mushkin Enhanced Redline in my i7-3930K build, and it has really paid off when I bust out Photoshop and Illustrator (and especially with VMWare Workstation!). You can always start with something cheap and upgrade later, I suppose, but RAM is where Adobe's products really like to stuff their plate full when they go out to eat your computer.