Anything on stdout goes to /dev/null, but in this situation, anything on stderr will still output.
What do you mean by:
how do I know if my system is able to execute bg process ?
Are you asking whether or not your system can execute background processes full stop? Or whether the particular task can run in the background?
General rule is that if it is going to want user input, don't run in background. All tasks, however, will run in background.