Regarding point 3, it sounds like you are asking about spritesheet support at an actual mesh level (3d mesh), in which case, unless I’m missing something, Babylon still does not support yet with instanced meshes. I.e. Spritesheet support for instanced meshes take 2 – Unless I am misunderstanding, or unless you are looking for 2d only (in which case sprite manager should work fine).
I’d still kill for instanced mesh sprite support built into the framework @Deltakosh 