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Ok, you have many questions, so let start. Shall we?
1) Holographic display are for the in-house and close combat engagement where one should prefer not use iron sight alignment and use both eyes and said eyes are open. No need to cheek-the rifle stock. As long as your can put the Holographic sight on your target, you are good. Said sight works well in low light as long as you can ID your target.
2) For hogs, most likely you are shooting at night and to see the cross hair you need a illuminated fire-dot or illuminated full cross-hair. At night you need to paint your target so you can see your hogs. As such, a green laser flash-light or green-laser painter with adjustable beam is needed.
3) For hogs, shooting range is usually less than 100-150 yrs so. a low variable zoom scope is best 4X-10X would be good.
4) For hogs, you may go with night-vision scope if you can afford Gen2 or Gen3 technology. It would cost $2,000-$3,000.

For target shooting any decent $400 to $800 scope from Vortex/Leupold/Bushnell/Burris would work fine. Optics clarity and low light visibility is you want. Zoom of 4.5-18X or up to 6-24X is more than enough for 100-300 yrd range.