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 (..as 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..