Spawning Decals That Look Good

Hi I’m trying to spawn bullet hit location decals. Ive got them to spawn but I have found a couple of small problems. So I have a couple of questions:

They are very hard to see in shadowy areas I could rectify this by spawning 2 of them one on top of another but this would lead to performance issues. Is there anyway to make the decal look more solid when spawned and not as alphad.

Is there a way I can stop the decals spawning ontop of each other once I have this issue solved? as the materials I use have the texture colour to the emissive colour because otherwise they are very very see through and the more that spawn ontop of each other the more the decals glow. I also have this problem with my blood decals.

My bullet decals are single textures and not Uv’d so I am making a material for each texture as I cant change the texture in a material instance…Is there a more productive way to do this apart from making them a Uv sheet. If not what are the standard Uv sheet sizes so I can attempt to make one myself.

Here is a pic of what I’m doing: