...I hear people who put on these aftermarket coolers and end up doing one or the other....
Well, let me give you the scenario. I installed a Thermalright TRUE Rev C on my CPU and it was not lined up with the rear fan of my case (by about a hair--I know very anal but i could see it wasn't lined up) and it was already screwed down with the spring loaded retention mechanism. All I did was 'motivate it' to move ever so slightly so it would line up.
Any risk of CPU or CPU socket damage?
No. I used both the horrible push-pin design on my ST-1283 and also the bolt-through kit many times without any damage to my LGA-755 CPU.
Once it is in, the CPU locking mechanism compresses the CPU against the pins and there is no chance the CPU can move or twist?
Sorry for beating this one to death....
Well, I've cleaned my CPU while it was locked down on my motherboard and it never budged in any direction while applying a bit of pressure with a coffee filter and alcohol to remove the thermal paste.