Raven (Elysian Angel)

This is by design. None of the ED modules have a working sunvisor despite several of their modules having one IRL by default (F-16 and -18, but several levels of tint are available for RL helmets apparently). The later modules all have working animations for raising/lowering the visor without it having any effect.
The community has been asking for this for over 8 years now, and ED has always ignored such requests, locked the threads or moved them to a different part of the forum.

Now things are changing: the upcoming MiG-29 will have a working visor, and ED have hinted at the technology being ported over to their other modules. This is what they said as a reply to my question on FB for example:

 

This actually might have been a driver bug: disabling ReBAR and then enabling it again fixed it. I'll leave this open instead of deleting it in case it helps anyone else.

I had this same problem today with the AH-64D Sinai Take-off IA mission (which had always worked just fine but suddenly became unplayable with just 21 fps) until this disabling/re-enabling of ReBAR.

I don't know if you have seen following video, but I think it sums up pretty well what we can expect:
 

Personally, I don't expect any benefit with the first iteration either. It will likely be purely to test compatibility and to make sure it doesn't break anything or causes unforeseen issues.
Later on ED will refine it, and as Wags has stated in multiple interviews: Vulkan will allow them to add a lot more effects to DCS which are currently not possible - including raytracing but also FSR 2/3/4 for example (DCS currently only supporting FSR 1 is due to the limitations of Direct3D 11).

Additionally, you can check out this thread here where people have been discussing the same questions you have for years:
 
 

Do you have FFB disabled in the "misc." options menu?

Works just fine here, and I’ve been flying the Kiowa pretty much daily from cold start these past few weeks/months.
What is your procedure? Double tap the “MMS manual/slave” button and it will move from stowed to forward just fine 🤷‍♀️

Likely an oversight, since the nVidia splash screen is shown on DCS startup. On the other hand, I don't know if there are any specific requirements nVidia has before a title is officially supported by their app.
If you don't want to wait for that to happen, you could try your luck with nVidia Profile Inspector.

Yes, as the third question in the FAQ confirmed. It’s completely separate from the FC3 version which will continue to exist independently. 
So you can pick whichever you prefer 🙂

Same with the FF F-15C really. To be fair this is easily done yourself (I have done it multiple times myself with FC campaigns), but having a professional go over any bugs that have arisen in the time since original release is certainly not a bad idea 🙂 

Yes, as is confirmed in the Supercarrier FAQ:
 

Yes you can:
Make sure the little tank icon (show models) is ticked in the Mission Editor

Have you looked at the track yourself? You are indeed skidding: you can clearly see that even in cockpit view, but I played through the track a 2nd time in F2-view and then you can clearly see the nosewheel dragging along trying to plough through the runway 😉
I suggest you re-centre your nosewheel before hitting the high-gain button. I think you were hitting that *while* in a turn, which is a mistake. You'll have the same thing happen in the Hornet: centre the pedals before hitting 'NWS HI'.

Known issue: there are other threads about it already.

Our Huey (and most other older modules) use graphical technology from the DCS 1.5 era (afaik our MiG-21 is still stuck in DCS 1.2). It doesn't support PBR etc that was introduced with DCS 2.5 in early 2018 (more than 5 years ago). It creates issues with how the current lighting model interacts with the materials, for example.
ED have stated numerous times that they plan to update all modules up to current standards, but it's taking MUCH longer than most people like...

Hey,
 
There are several "cockpit liveries" available for download in for example the "User Files" section of the official DCS website. Some people also make their own, with a few added decals etc.
 
Personally, I use a combination of 2 different cockpit mods: one with mipmaps removed for increased readability in VR, and clearer green cockpit glass in anticipation for a new cockpit model by ED that supports DS/PBR.
 
No so, there's no need to worry. Yes it's an old module that doesn't support changes ED made to DCS over 3 years ago, but we're all in the same boat 🙂