Basically how would different vacuum pressures affect incandescent lamps? Is there such thing as high and low pressure incandescent lamps? Does it affect efficacy in any way or does it not matter to a filament?

High pressure - slows down filament evaporation

High pressure - higher thermal losses, but at the same time enables to drive the filament harder so more efficiently

Hig pressure - higher breakdown voltage (to prevent arcing during lamp life)

High pressure - slows down filament evaporation

High pressure - higher thermal losses, but at the same time enables to drive the filament harder so more efficiently

Hig pressure - higher breakdown voltage (to prevent arcing during lamp life)

are halogens high pressure lamps?

Also if the pressure slows down the evaporation of tungsten is there a point where it could prevent it period?

Halogen lamps were initially high pressure of the halogen (10 bar), but owing to the explosive EOL of these lamps in these conditions, mains voltage halogen lamps, have a lower pressure of the halogen (2 bar). which reduces the likelihood of explosion at EOL, at the cost of lower efficiency.

Also if the pressure slows down the evaporation of tungsten is there a point where it could prevent it period?

Generally no pressure could ever stop the evaporation, period. To any temperature correspond certain equilibrium in partial tungsten gas pressure (the amount of evaporated atoms is cancelled out by the amount of atoms sticking back), but in any liquid environment a diffusion will happen, causing the gas to spread around. It is the speed of this diffusion, what is slowed down by the presence of the gas fill (when the gas diffuses out slowly, around the filament remains relatively high tungsten pressure, so the net evaporation is slower). But any gas or even liquid fill may just slow down the diffusion, but it is never able to stop it completely.
So it will just always evaporate, the matter of the gas fill is just how fast.
And in case of a chemically active atmosphere (e.g. halogens) there could happen some mechanism moving the tungsten back onto the filament (e.g. halogen cycle, chemically dissolving the tungsten from colder places and bringing it to the hotter filament), so it is cancelling out the evaporation. But then usually the same effect is attacking the colder filament parts, or the filament fails due to local electromigration and cracks.

It's pretty much impossible to make a filament that will last forever, and have a decent efficiency, and realistic costs, so it's a balancing act by the manufacture they aim for a good life span, cheap and about the best efficiency you can realistically get from a tungsten lamp, and it's much easier to reduce tungeten evaportation by just using a dimmer switch and starting the lamp dimmed and increasing the power level but limiting it below it's full ratings, while you get a dimmer, more orange light, the bulb will last a very long time, but don't use Halogens dimmed for long periods of time they will blacken and then you need to run them at full power for hours to clean them up..   

There used to be some fairly recent (2000's) advancement in the area, iirc they managed to make ~40 Lm/W Incandescent with decent life by making some sort of flat filament. I dont recall the detail though