1) Is it possible to close only that file(book), which is currently open with Windowse close (X) button in the right upper corner, without closing other files(books) of Excel

2) I think this question depends from 1st one:
- When I'm working and I've done several mistakes, I can use UNDO (Ctrl +Z) function of Excel. But when I use UNDO it returns back for one step and it can be changed also in other files (if there are opened several). But I want to back datas only in this file, not others.

3) I wrote simple Macros that shows message box. Is it possible to run this macros when I'm opening the file. I mean when I open the file -> that MsgBox is shown. How can I do it? Or Should I add some codes in VBA?

Questions look like a little bit crazy , but I'll be very glad to know how to do that .
Thanks a lot.