How to start executables through command prompt with space named files and without command prompt waiting program to close?

Read help for start carefully. And start does not wait for started process termination by default (there is /wait flag for "waiting" mode).

start "" "Foxit Reader.exe"

Start seems to take the first parameter as the title if there's a space in it.

So while this did not work for me:

start "c:\Program Files (x86)\Foxit Software\Foxit Reader\Foxit Reader.exe"

This did: start "" "c:\Program Files (x86)\Foxit Software\Foxit Reader\Foxit Reader.exe"

Use quotes like this:

start "" "Y:\foo bar\xyz"

If the first argument is quoted, start assumes it's the title for the new console window, so launch a new console window. The following argument will then be correctly interpreted as the command to run / file to open.