Who can lodge an FIR as per IPC 182

I am an Army officer , a vendor had written a false complaint of manipulation of GEM procedure and taking undue advantages of taking comission (corruption) . An Inquiry was put on me . All my documents were checked , procedure and even my bank accounts . Further , the complainant was also question through videography since he could not come and said that he thinks he must be doing such things and has no proof of same . The conclusion of inquiry was the complaint was found to frivolous and devoid of any merit . As per the Vigilance authority of army , directions has been to lodge an FIR against the vendor My question is 1. Who can lodge the FIR now , the complaint was written to my CO and his seniors of rank of brig , Maj Gen And Lt Gen . Further , I work under the command of my CO 2. Where FIR should be lodged . The complaint letter was written in Kolkata , Delhi , Dimapur and Imphal 3. Is departmental inquiries are enough for lodging FIRs 4. What is the Validity period of Defamation case