Is there a limit to how many mods I can merge, or do I risk errors the more I merge? I have about 10 different single ESP mods (ie no texture/meshes, just lone ESP's) That I'd like to merge into one convienient ESP, none of them have any strict load order, should it be safe to merge them?

If all those mods loads fine in CS together, then you can merge them without problem. Actually, rather than worrying about errors, you have to worry about mod conflicts, like mods changing same objects or if they modify dialogue, you have to make sure they don't change same topics and as such.