A question on assets...

Currently I am making 3D assets in blender for unity however the are a few things I need to clarify.
First do i bake and make normal, specular, ao and diffuse as different textures, and just apply them all to the model or do I combine them into one texture then import to unity?
Also what size should I do the textures baring in mind that the game will be played only on PCs, its for a fighter jet so it is quite large, the player will be able to walk up-to it and being a space game the is relatively few other assets. (should i just make them huge and scale down once in unity, if necessary?)

I’d make the textures 1k or 2k resolution. You probably don’t need it much larger than that unless you’re really zooming in on the ship. As for baking, I’d probably bake everything prior to going into unity. You can use shaders for different effects but for things like normal, spec, and AO you might as well bake them in blender. This way you get exactly what you want in the engine.

As for combining, I’d recommend combining them all into 1 texture when you make the model. That would be the cleanest way to do it.