Is baking necessary?

To Bake or Not to Bake…

Often baking is based on a performance or technical need rather than an artistic need from a general perspective.

So you have a number of things going on in your scene: lights, textures, animation, etc. Each can be baked and baked separately and they all have different results and reasons for doing each.

So the following is a general guide but its just that…you can break the rules to suit your needs.

Lighting – For V3D the best answer is – dont use lights. Its expensive to your performance efficiency. You will want to use and HDR Environment Map(s) for your scene.
This is until you have an interior scene … where you may have an office space with hundreds of overhead lights…..then my answer is still to use an HDR Map and no lights.

To get the lighting effect you need this is where you will bake your textures with lights, shadows, ao, etc to get the look and feel you want of your scene. Use these textures and remove all the lights and EEVEE and V3D will look like your Cycles scene. The Escape Room doesn’t use any lights but has all the lights baked in the ceiling…take a look.

Escape Room

Skydomes are Environment Equirectangular textures…you can do some simple map changes as needed in your scene but just don’t animate them.

Ok…on to the reflections in your scene dont work.
There are many reasons why the reflections in you scene may not be working. We would have to see the blend file and review the setup and materials etc. to determine why.
Are you using light probes?

Light Probes

If not give those a shot. Do not use the Screen Space Reflection setting in Blender as those will not be processed by your V3D GLTF export.

You should also be sure to set your ColorManagement in Blender to Standard.

Hope this helps.

Unfortunately, all the answers are subjective. Without actually seeing your scene and without knowing what you are trying to achieve I can only offer suggestions.

You do not have to bake the light if you are using just environmental lighting. The idea behind baking the light is to capture shadows. If thats not necessary skip it.

Baking textures is not required but if you are wanting to capture AO, shadows and other details and maintain the quality of the render like you seen in Cycles then yes…you will want to bake textures. However if you are using screen space reflections and what not…skip it.

If you change your Environment texture you will need to use a light probe in the scene and then update the light probe when switching the environment. This too is subjective as there are many ways to achieve the look of swapping the environment background and having the it affect the scene. Again depends on what you are really trying to achieve.

Screen Space Reflections that are in Blender do not come across in V3D so you can turn them off. ScreenSpace Reflections will be handled in V3D as a post processing effect.

Just keep in mind that what works in EEVEE should work in V3D but not everything.