While the Razor red-dot does not have a motion activation feature, the new Defender-series red-dot does! Check it out here: https://www.opticsplanet.com/vortex-defender-ccw-1x-moa-red-dot-sight.html
Picatinny mounts will fit onto weaver rails, but not vice versa.
Yes, this would work well as long as you have a picatinny rail to attach it to.
The Vortex Razor Reflex Red Dot Sight will not fit the Glock 43X. MOS Models of the 43X will be compatible with optics that use the RMSc footprint such as the Vortex Defender CCW, Sig Romeo Zero, Shield RMSc and more.
Since the Vortex Razor Reflex Red Dot Sight includes a picatinny rail adapter, you would not need to use an additional adaptor. A riser wouldn't be necessary either unless your optic was obstructed by another accessory in some way.
The SightMark LoPro Mini Laser Sight may interfere with the line of sight of the Vortex Razor Reflex Red Dot Sight if mounted directly in front of it. I recommend using a riser mount with the Vortex Razor Reflex Red Dot Sight to prevent this. The mount located at the link below will work.
https://www.opticsplanet.com/american-defense-manufacturing-ad-sf-w-sf-rail-mount-for-small-red-dot-optics-bu.html
The Vortex Razor Reflex Red Dot Sight uses the C-More mounting footprint. So it can be mounted to anHK VP9 OR using the compatible mounting plate from HK. The mounting plate you would need is plate #03.
The red dot size of the Vortex Razor Reflex Red Dot Sight is really personal preference. The best reticle will depend on what you are using it for, your eyesight and the distance of your target. With that being said I would suggest using the 3 MOA Vortex Razor Reflex Red Dot Sight because it will most likely suit a wider range of shotgun applications better than the 6 MOA reticle.
Yes, the Vortex Razor Reflex Red Dot Sight can be mounted to the picatinny rail located on the Vortex Spitfire 3X Prism Red Dot.
Yes, the Vortex Razor Reflex Red Dot Sight will fit but you will need this mount.
https://www.opticsplanet.com/evolution-gun-works-vortex-razor-mount.html?_iv_code=KK-RMT-VRMSM-49445