I would not pay them to OC your CPU, you can do it just fine. Also you need to leave your CPU at default clock settings while you load FSX and all addons. I would leave everthing at default until you get all programs loaded that you are going to load. Then you need to let everything run for at least a month, if not two, before you start overclocking. This way if you have a problem with a program running after you overclock then you know the problem probably is related to your overclock. Overclocking a PC is a subject that can take a thread of its own so that is all I will say here. You are not going to degrade your 2600K by overclocking it as long as you do not overclock it higher than it can run safely 24/7. All chips are different, one can run at 5.0GHz at a certain vcore and another can only run at 4.6GHz at the same vcore. It is the luck of the draw. The point is you do not overclock it any higher than what it takes to run it at a safe vcore. There are other voltages, but I am not going to get into all of this now.
The 6GB of ram spec is from the i7 9XX days, to run at optimum your ram had to be 3GB, 6GB, 12GB, etc. With SB you need 4GB, 8GB, 16GB, etc. and for FSX 8GB is all you need. No one know about Flight at this time, but I would think 8GB would be more than enough for flight.
The only problem with putting both the OS and FSX on the SSD is room. My SSD has 50GB on is, all I have is Win7, Office 2010 and a few other programs that I wanted on the SSD. I have two drives for FSX, the FSX drive has 110GB on it and the other drive that has nothing but photo scenery has close to 300GB on it. If you put your OS and FSX on the same drive you will be limited to the amount of FSX addons you can add. From what I have read in FSX hardware forums other than faster loading times most people do not see a performance difference with FSX on a SSD. If you want FSX on the SSD then all I would put on the SSD is FSX. If you think that you are going to get a bunch of addons over time then you maybe better off putting FSX on the HD, but I would partition the HD and put FSX on the first partition. This is also a subject that can take up a tread on its own.
FSX will let you set the resolution of your monitor. You just need to make sure that the resolution in Win7, FSX and the Nvidia control panel are all set to the same. The monitor you show has a resolution of 1920*1080 and that is not a problem setting in FSX. My monitor has a resolution of 1920*1200.
Regarding overclocking, you need to stress test and monitor your temps while you are doing it. You should read a couple of guides before you start. A great hardware site is
www.overclock.net and there are a great bunch of people ready and willing to help you out.
What case you get is up to you, what does not look good to one person looks great to another. What you really need in a case if you plan on a high overclock is airflow. The two cases I recommend are two of the best in their price range and since I have had them I can recommend them. Overclock.net has a case forum and if you see a case you like you can post over there and ask the forum members what they think of the airflow.
Asus R3E_i7 980X @ 4.44GHz_TR Silver Arrow_Mushkin Redline 6GB 1,644MHz @ 6-7-6-18_Zotac AMP GTX 480_OS - Windows 7 Ult 64b_OS SSD - Crucial C300 128GB_FSX HD - WD VR 600GB*2 w/3ware 9750-4i 6Gb/s Controller_Corsair AX850_CM HAF-X_FSX Gold, UTX, GEX, FSG,