Vanquish Level 4 Pre-Purchase Questions

Hi guys,
I'm planning on getting a new computer from DSO (Vanquish level 4 to be specific) and I'm one of those people who has to know everything about something before I buy it. I just have some quick questions.

I've been looking around the forums and noticed that some people are having issues with OCing causing BSOD or overheating or some other problem. Should I be worried about these kinds of issues happening or is this more of a game related issue? The most heavy graphics game I'll be playing will be Metro Last Light (I'm not sure how well the level 4 can run it).

Another issue I've seen on the forums is that some internal parts may not be mounted properly or loose which causes problems. I'm not exactly sure what to check for in terms of knowing if something is loose or not and how to fix it. Any advice on this would be nice.

Last question - I know the computer will be pre-setup with everythinng, but are there any things I should install/fix before I start heavily using my computer, or can I just "plug n' play"? For example should I update my drivers etc...

Actual last question - in terms of this as a long term investment, how well do you think the level 4 will be able to play games say 3-4 years into the future? Will this rig still be able to run games at medium+ graphics?

Kind of a wide array of questions but I would greatly appreciated if a few of them are answered. And just for clarification I won't be changing anything in the system, it will just be whatever comes in the pre-built Vanquish level 4.

Thanks!