Disassembling an old Desktop PC-questions

[Mosbonian]

As part of my retirement fun, I am delving in to learning more about salvaging old computers/computer parts, to see if it is something I would like to do.
I am starting with one of my old desktops that I kept around for many years.... and old HP 6470 desktop.

But I have questions that I am sure many of the computer geeks can assist me with...so here goes:

1) It was pretty easy to disassemble save for one part....a storage drive that I swear must have been welded to the frame or front plastic casing. Any of you tech geeks know how that thing is installed?

2) I have read a couple of books, watched several vids on Youtube and I am still a bit confused about which parts of the PC could still have bits of data that I wouldn't want to get out there if I piece out the parts to computer guys who may buy them from me. It has a zip drive and an old CD player which I don't think would have any resident data on them...but what about things such as ribbon cords, RAM, etc that I have taken out? I know there is software supposedly that you can install that clears out the data, but this old PC wouldn't boot up anymore.

3) This also has 2 fan motors.....are those things useable anymore?

I realize asking these questions makes me the possible butt of many jokes...but would like some of you who might assist/educate me to weigh in if possible.

Thanks,