I mean, a difference between using "Combine taskbar buttons" -> "Always, hide labels" and setting all of the taskbar items to hide labels using taskbar inspector.

And all unnecessary windows will be restored instead of being still minimized.

If you click once, only the last active window is restored. (Maybe you're using "Restore all group items"?)

The unused windows for some reason are forcing themselves to be restored instead of the recent one.

Perhaps your specific app works that way. You can try it with another app such as notepad and see that it restores one window at a time.

And why "Switch to" command for combined items works as thumbnail preview instead of switch to recent window?

That's how it's implemented. It's true for all options - "Switch to", "Minimize", and "Close". I can consider adding a new value to taskbaritem - "Cycle through windows".

You forgot about option to hide labels & combine when full.

OK, that's a valid argument.

And Icons too.

I still don't understand what difference is there between using "Combine taskbar buttons" -> "Always, hide labels" regarding icons. Please show me a screenshot that demonstrates the difference.

I don't know what is a virtual desktop and how it would help me.

https://en.wikipedia.org/wiki/Virtual_desktop

But it cycle throw all windows in sequence. I don't want to switch to other windows at all, only the main one from that group.

Yes, it's not exactly what you're asking for, but if you click once you'll get the window you want.

Not activate minimized widows. I meant other window (different application and group).

That works properly for me. I opened a Chrome window and three combined explorer windows. Then I minimized the explorer group, and Chrome got focus. Just like it happens if I right click on the explorer group and choose to minimize all three windows.

So you want the taskbar to behave as if every item has a different AppId, and still not show the related pinned item if the program is running. What you're asking to do is tricky, and will require a lot of time and research, which I don't plan to invest. I know that because I had more trivial issues related to pinned items, which were quite time consuming to fix to fit the tweaker's options. Remember that explorer is not open source, the tweaker is expected to work on every build from Windows 7 to the latest Windows 10, and many things are implemented with a bit of creativity and hacks.

OK, then the icons example is unrelated. You provided it as an example to - "items behave differently when Windows' option to hide and show labels are used" - but they don't behave differently.

Why not add such an option:

1. It will have to be implemented, i.e. I'll need to spend time on this.
2. It complicates the tweaker.
3. It adds work for me to do every time a new Windows build is released to keep the tweaker compatible.
4. It's already possible to do by using the taskbar properties. You said it's different, but I don't see how.

Why add such an option:

1. More options to control from a single location which is the twekaer.
2. Can be used with the portable version of the tweaker on others' computers.
3. ???

So, as you can see, there are at least several reasons as of why I'm reluctant to add this option.

The website is accessible on my computer. Please try again, and if it still doesn't work, please provide more details, such as the error message that you're getting and a screenshot. 

I remember that it was possible to disable the hover preview in Windows 7 from the system settings. Now I found these threads: one, two. One of the comments mentions about one of the solutions that it doesn't work on Windows 10 anymore, so it might not work for you. Try it out, and hopefully one of the linked answers will help you. 

if an application opens few windows, but only one (main) window is I use and the rest just need to be there for application to work. I can minimize the rest

You might want to try using virtual desktops for this scenario. They are built in since Windows 10, but since you're using Windows 8 you can try Virtuoz (a minimalistic virtual desktop utility developed by me) or any other virtual desktops tool.

But with left click not always work like should. Instead to switch to main window it displays thumbnails (even if inactive) or restore the minimized other windows that I don't want to use.

You can try the "Left click on combined item" -> "Cycle through windows" option. This will open the last active window when you left click. You can also use Ctrl+left click.

Also minimize all windows from group works bad, cuz it's not activating other window like normal minimize does.

Why would you want it to activate the minimized windows?

That might force the same icon for the rest of items

This happens if you choose to hide labels, and is related to your previous post. See my answer there.

move the pinned item position to the most right item on exit/restart

This happens because pinned items are "grouped" to their instances by AppId. If you don't want the two to be related (so that the pinned items won't disappear when an instance is running), use "Don't group pinned items".