Could anyone comment about the most minimal ways of looking into my computer while not being detected?

Some background: I work in a public work space and have my machine open at home. I take the standard security practices: strong password, prompt upon waking up, try to lock up my work computer.

But we got talking with a colleague of mine earlier this week.

Just suppose someone had the ability to enter the Admin password and look at the desktop, Dock & Finder. One machine I have has had the rights passed onto my IT group for access. If someone had a USB and mounted it where it showed up on the Finder, does this only show up under `Recent Items` while the USB is mounted?

What if someone were to use Searchlight... Cmnd & single click just to get an overview of the file? Being that is a preview, was it really 'opened` in order to show up on Recent Items?

One step further- what if you did a Search.. found a file you were interested in.. and then dragged it to the USB and then unmounted the USB? Would this action show up in Recent Items ( it was not really opened?)

How could a co worker find a project and drop it onto a USB with very little record of it in Recent Items?

Do you see where I am going with this? I am interested with the experts here about how you could find files in Search and `copy` them by dragging to a USB and unmounting the USB.. as the file was not really opened.. just `previewed`

I do know that there is certainly a track record via Terminal.. but I don`t understand that stuff nor the commands. I also know that if I were to look in Safaris Cache that there would be records of websites. But that isn`t the case-- I am more interested in someone finding files and copying them.

And in my limited Mac experience -- what if someone opened a file.. closed it completely (Cmnd Q) and then cleared the Recent Items list and then just re opened the files he found when he first looked at my computer (when I was in the washroom or away for more then a few minutes..). Once I returned would it not appear when I check Recent Items that very little was opened? I hope I am explaining this right. English is my second language

For the record, I asked our one man IT department and unfortunately I just got an answer in Klingon and then he talked about Code. To be fair his background is in Linix. My job is marketing & find the mac intuitive.. but I am just not up to speed on these things.

Thank you for reading..