Can the employer hire someone for the same position whilst an unfair dismissal case has been lodged and a conciliation date set? Also, the employer has not responded to the application back to fair work within the 7 days..
Legally they can. However if you obtain reinstatement as a remedy they will have to either keep the other person or terminate their employment which may give rise to a claim.
If you want me to take a look at your case I would be happy to no obligation.