For the purpose the asset has been made, that is not required.

If you need the skin mesh water tight, fill the eye sockets with a triangle fan.

No.

The asset is designed to be used in offline animation projects, within Blender.

Yes. Meshes and rig are compatible with Blender 3.x.

However there has been a compatibility break between 3.3 and 3.4 within the shader node system - the color mix node has changed. In order to use the asset in pre-3.4 versions, all the undefined (red) shader nodes in the materials need to be replaced by MixRGB nodes, the  respective settings adjusted to match their 3.4+ counterparts.

To save you the trouble, there's a file "materials-3.3.blend" included in the package. Append the materials from that file into raccoon.blend, and assign them to the appropriate material slots.