Heightmap Fields and RGB raw files

1. Went to L3dt and noticed that when change that number changes the size of the map say a 2048 x 2048 that is a 20x20 kilometer with a height field of 10.00. But is change the height field map say to 2 it becomes a 2048 x 2048 with a 4.1 x 4.1 kilometer map.

How much does the heightfield effect the map , is the map at this point being stretch or what is happing here?



2. Can any one confirm the correct way you combine the raw files in photoshop? From what I readed that RGB + alpha creates a 32bit file in png format. Copy my raw files into the RGB + alpha fields in the channels and save it , but also I found out that the alpha is the highest field in the map and R is the lowest field. Is this information correct?

3. On the maps you only use 4 colors in the map due to the RGB + alpha ? Hoping this not the case due this lack the ablitily to color a map in various multi colors. If this is the case does this mean have to create smaller maps for those zones? Hope this does not limit the various ways of coloring a map...