I'm not a complete idiot when it comes to computers but I don't have access to an IT department to advise me at the moment,
There are so many options so any suggestions on the configuration would be appreciated.
Processor, Ram, Hardrives, Graphics card?
While you don't have an IT department, you probably do have a budget. That is capped by the expected revenue ( or ability to charge back into org that does generate revenue). That is going to put some boundaries on the problem. It is very easy on these forums to configure a $20K workstation system with associated peripherals.
There is an issues associated with "fastest processors you afford" that aren't really being touched on here. You shouldn't get into a point where you are "Robbing Peter to pay Paul". Too much allocation to CPU spending probably will decreas RAM , Storage , and Graphic card capabilities because will be out of budget.
It doesn't really pay to heavily skew just to the CPU. Make sure to account for enough RAM , storage and graphics to be adequate and then deduct those from budget to see how much "play" you have with CPU prices.
That should lead you to a closest match default configuration if can't settle how to manage the more CPU vs. better RAM vs. better storage vs GPU tradeoffs.
FCP 7 vs FCPX makes as different in not just the RAM usage but also in effectively leveraging the GPU. Video ("graphics") rendering that doesn't make use of the GPGPUs doesn't make a whole lot of sense. In the past, that was true but for modern 2013 apps in this space not to leverage OpenCL is
huge head scratcher. Having a giant bucke of flop ops that need to be done doesn't necessarily mean x86 cores anymore. Yeah there are apps and plug-ins with comatose development coupled to them but unless trapped on those it is quirky to let them drive future hardware purchases.
FCP 7 has upsides if have a significant legacy library of older FCP projects or need to interchange projects with people who have such libraries. If you are primarily doing your own stack scale would tip toward FCPX.
After Effective is become more GPU card balanced (not so CUDA biased ) but again depends upon what will be using it for in short term. Longer term that should disappear.
Storage can be an issue because the more you have the more you need to back up. If your projects are in the 100GB range then SSD (or two) may be better fit than looking at RAID solutions for the active working sets.
Another storage question to ask yourself is how much do you need to keep on nearline storage ( need fast access to last 6 months of work. last 12 , or everything ? ). It is alot cheaper to archive stuff not gong to look at for a long time onto an detached external 3-4TB drive than it costs to keep it spun up and active on a RAID-5/RAID-6 set up.