Re: A few questions?
THat is true. Most other parts will be interchangeable with the except of process and ram (even those and interchangeable but you have to get the same sock type).
As for the hard drive the only time you can 'plug and play' a hard drive from one PC to the other is if the manufacturer of both motherboards are similar and require similar drivers. Otherwise the OS will not load because it won't know what hardware to load at startup.
Google what part you want to remove and there will be hundreds of videos on youtube on how to remove that part.