What do you mean by "tabs" ? Like browser tab type tabs ?
Yes. Tabs like in an internet browser, but in the file explorer (called nautilus in Ubuntu). No more having eight copies of explorer open. I eventually cracked and went hunting for the next best thing in my W7 computer at work, but it's clunky and invasive. In Nautilus it's just..... nice.
Copying files in windows between nearby folders = open file explorer and, starting from scratch, browse to FROM folder. Open second instance of explorer by clicking on Start. Browse to location again from scratch (or copy/paste address if you're clever) and go to TO folder. Drag and drop files.
Copying files in Ubuntu = browse to FROM folder. Middle click on TO folder. Drag and drop files.
About half the total number of clicks.
And how hard would it be for someone to figure out what it is by hacking or other means?
Depends if you use a hard or a soft password. I'm no hacking expert. But my understanding is that if someone doesn't guess your password, or have physical access to your computer, then it's considered secure.
What are some advantages to that besides not having to delete everything in that particular drive when you uninstall the OS?
Isn't that enough? There's no pleasing some people ;-)
I'd say the biggest other advantage is also the answer to your next question.
would you be able to have a hard drive that just has a bunch of different variation of Linux on it? Or would that not boot correctly?
This is, in fact, what I would recommend. I have one partition that just has my /home folder. On two other partitions I have ubuntu and xubuntu respectively. They both mount the same /home folder, which is to say that they don't just have access to each other's files - they access the SAME data files, it's the exact same folder setup no matter if I boot up into Ubuntu or Xubuntu. The "Grub" bootloader is currently set to boot into ubuntu, but it is a moment's work to change it to xubuntu.
I have it set up so that I can run ubuntu 99% of the time but if the mood ever strikes me I can play around in Xubuntu (actually I'm tempted to do this as my machine gets older and older) or I could wipe it and have a go with Debian or Mint, and unless I screw up and install into the wrong partition it won't have any effect on my family's ongoing day to day computer use. Or, the way it's set up, if ubuntu goes wrong suddenly and I can't be arsed reinstalling, I could just throw my hands in the air and switch to xubuntu, no problems.
Someone in my house (probably not me) may or may not be in the habit of doing regular practices normally reserved for people with a peg leg and a parrot on their shoulder, and all of those files go into a seperate 2TB hard drive in my computer. Unfortunately for me, like I said I have a cheap and nasty machine that has regularly let me down, so I have to have it all set up so that a failure of one part probably won't fuck the whole thing, and so far I think that I've been more successful with that than I would have been in windows.