KDE is the answer to both of your questions.
2) While in stock form on most/all distros, KDE is set up with the same destructive window closing button issue as Windows and Mac, it's easy to reconfigure it to change the locations of all the window buttons. You can add some extra space between the close button and the minimize/restore buttons, or you can even move the close button to the other side of the window if you want. It's completely configurable. They probably keep it just like Windows/Mac to avoid confusing people.
6) The start menu (actually "K menu") in KDE is organized very well. When it opens, the first tab is "Favorites", and shows your most-used applications, plus a box where you can type in the name of an application to search for. Or you can switch to the "Applications" tab to get to a menu of all your installed applications. In there, all the applications are grouped according to their function: Development, Games, Graphics, Internet, Multimedia, Office, Settings, etc. This is completely unlike Windows where all the applications are a big mess, only grouped by the application's maker with no indication as to what it actually is or does. Then, inside one of these groups, each application has its own icon, plus is usually listed by its description, along with its name, such as "Image Editor", and then in smaller gray text, "GIMP Image Editor"; or "Media Player" and "Kaffeine" in smaller gray text; or "Spreadsheet" with "LibreOffice Calc" in smaller gray text. (note: some of this is probably distro-specific. I'm using Mint KDE for reference.) A new user doesn't have to know the name(s) of the spreadsheet programs on a Linux/KDE computer like this, he or she just needs to open up the K-menu, go to Applications, click on "Office", and then look for the programs that say "Spreadsheet", and LibreOffice Calc will be there (along with any others; that's all I have on mine at the moment). OR, they can click on the K-menu, and type "spreadsheet" into the search box, and all the spreadsheet programs will be listed there for selection. OR, for a shortcut, they can type Alt-F2 which brings up a litle search box at the top of the screen, type "spreadsheet" into that, and all the spreadsheet programs will be listed there. In my case, since I have only one (Calc), when I type Enter it automatically launches Calc. Windows doesn't do any of this stuff.