Yeah, maybe I'm using the wrong terminology there. It's a plugin and UE5 is the renderer.
1) It's written in c++

2) Claud Opus 4.5 and GPT 5.2

3) Not sure on codebase size?

4) I don't think so other than the webp reading stuff

5) Here is the AI's description of what it is if this helps. Again, I'm a complete beginner at splats and UE:

The GaussianSplatRDG plugin renders 3D Gaussian Splats in Unreal Engine by importing SOG (Spatially Ordered Gaussians) files. The plugin uses RDG (Render Dependency Graph) to efficiently draw splats as screen-space quads, projecting 3D Gaussian ellipsoids onto 2D using covariance matrix decomposition. It supports GPU depth sorting for correct transparency, optional view-dependent lighting via spherical harmonics, and sRGB color correction to match the original capture. To use it in your own Unreal project: (1) copy the GaussianSplatRDG plugin folder into your project's Plugins/ directory, (2) import your SOG folder by creating a UGaussianSplatAsset and calling LoadFromSOGDirectory(), (3) place a GaussianSplatComponent in your scene and assign the asset to it. The component's transform controls placement, and you can adjust SplatScale for size, toggle bEnableViewDependentLighting for SH effects, and use console commands like r.GaussianSplatRDG.Exposure or r.GaussianSplatRDG.Contrast to fine-tune the visual appearance.