Lightmapping and iOS Shaders Guidelines

I am able to successfully create light maps, but still feel uneasy with how the light map is actually applied and which shaders I should be using for mobile/iOS development.

When lightmapping for mobile, should I still be using specific mobile shaders to set up the bake, or can I use standard diffuse and other shaders?

Does the light map get applied on top of the currently used shaders, or does it replace them completely with some magical Beast shader? (In the Angry bots demo, I noticed that the light-maps contained color info and my current maps currently seem just to contain greyscale values, so this was adding to some of my confusion.)

Are there any guidelines for how big the lightmaps should be for mobile? Are they handled the same as regular textures in regard to memory, or are they optimized in someway?

Thanks in advance!

 

Thanks for the helpful info Daniel. One more clarification if you don't mind.You say the lightmaps are just textures, does that mean the textures from the lightmap replace the existing textures on the materials, or is the shading from the lightmap applied in some sort of a transfer mode on top of the current shaders/textures, effectively combining the two shaders/textures?

Thanks!

 

Thanks!! Clears it up for me what is going on, which allows me to move forward and work with them more confidently. Much appreciated.