The Truglo RMR adapter would be compatible with your FNX-45 Tactical. You would need to install the RMR adapter plate to your slide and then install this adapter to the plate. However, because you have to install this to an RMR plate and not a slide cut, you would need to use different screws. I would recommend purchasing the Swampfox Ultimate Red Dot Mounting Screw Pack which can be found by using the link below:
https://www.opticsplanet.com/swampfox-ultimate-red-dot-mounting-screw-pack.html
Yes. This TruGlo adapter plate should fit your ZEV slide and convert it to accept the DeltaPoint Pro.
No. This mount will only fit slides that are specifically cut for the Trijicon RMR in order to convert the footprint to accept other optics. If you do not have an MOS model Glock 45, you can use the Evolution Gun Works Leupold DeltaPoint Pro Sight Mount to mount a Deltapoint Pro to your Glock 45. The adapter can be found by using the link below:
https://www.opticsplanet.com/evolution-gun-works-leupold-deltapoint-pro-sight-mount-for-glocks.html
No. This TruGlo adapter plate fits slides that use a Trijicon RMR optic cut and converts them to accept other optic models, including: The Leupold Deltapoint Pro, Sig Romeo 1 Pro, Eotech EFLX, Sig Romeo Zero Pro and more.