Setting vim buffer/window name

You can't pipe the output of a shell command into a command that creates a new buffer, but you can create a new buffer and read the output of a shell command into that buffer with one entry on Vim's command line. A working version of your example would be

:tabnew | r !echo <c-r>=bufname("#")<cr>

Note that the pipe symbol in this case is a separator between Vim ex commands, not the shell's pipe. See also

:help :tabnew
:help :r!
:help :bar

You can have Vim use the clipboard instead of the default register for yanking, putting, etc., by adding this command to your ~/.vimrc:

set clipboard+=unnamed

See

:help clipboard
:help 'clipboard'