>1) does a password-locked screensaver provide any obstacle to obtaining a ram dump?
no, the program simulates a crash, and dumps the RAM to the flashdrive that it ran from
>2) if the computer has full disc encryption, how often is a RAM dump able to successfully provide the decryption key?
about 1/5 times. Its not every time, but it has and does happen.
>3) is there anything that can be done (other than turning off the computer...) to thwart a ram dump?
not really. the RAM dump simulates a crash of windows, so, it kind of ignores everything.
>4) have you ever heard of anyone doing a successful cold boot attack (turn off the computer, physically plug in the RAM sticks to a specialized device to record their contents)?
no, not sucessfully. There are devices that we could get to do that, but a RAM dump is easier. even with full disk encryption, if its running when we get there, we can make a copy on site, while we have access(if im there to start), otherwise, idiot police officers just follow the protocol and unplug it. makes me rage every time.