Yes. The Vortex Spitfire uses the Aimpoint Micro mounting footprint, so this OpticsPlanet Exclusive Fortis Manufacturing F1 Optics Mount will fit and function as intended.
This mount will be very close in height to the QR base that comes with the Romeo4H.
Yes, this mount is compatible with the Holosun HS515CM.
No, this mount is meant specifically for Aimpoint Micro red dots and red dots that match the Aimpoint Micro footprint.
Unfortunately, despite being similar, the MRO has a different footprint and is incompatible.
Yes, this riser is compatible with that optic.
No, this will not work with the Primary Arms Primary Arms SLx scope. The reason it will not work is that this mount is designed for optics that utilize the same mounting footprint as Aimpoint micro red dots. The SLx uses a very different mounting footprint.
Yes, this will work with the Holosun 503C.
Fortis OP Tan is significantly more gold-tinted and brighter than Magpul's FDE.
Yes, this will work with the Romeo 4B.