Yes it’s the same as Ctrl+left click. Sometimes it’s useful when you don’t have your other hand on the keyboard, and I’m sure there are people who find clicking on the plus easier. And it’s easier to discover as well.
Personally I like to use keyboard modifiers, for example Alt+left click to move a window or Alt+right click to resize it. But most people I know drag the titlebar or borders to move/resize windows.

Same as the + sign in Dolphin – clicking on it selects the icon. You can disable it in Dolphin but not in Folder View, as far as I know. A possible (“hackish” workaround could be to modify the theme and remove the plus icons.

They just showed up suddenly. I want to make them go away as they are superfluous, and look sucky.

To me the KDE 4 experiment has been a “successful” failure. I much prefer the functionality of KDE 3.5.10. I’ll make the comparison as much the same as between Vista and XP. Some like Vista some don’t. Some swear by XP and wont go past it. I’m at the stage now that when KDE 4.5 comes out, I’ll probably look at it again.

I miss my Konquerer functionality, dual screens and themes. None of which feature in 4.2, or at least allude me. As regular participant at Distrowatch.com, I’ve decided to boycott any distro featuring KDE 4, until at least 4.5.

I have real work to do (running a business) and don’t have time to fully learn (appreciate) the nuances of KDE 4.2, when KDE 3.5.10 is perfect.

BTW. As I’ve stated, I do appreciate the work the KDE team and community are doing at progressing KDE 4 into a mature DE. It’s just not ready for me yet ;^)

I’ve tried retuning to KDE 3.5 but failed. So, I’m back to 4.2 and will live with it, until either I “get it” or find more documentation.