No it won't add to the drawcalls. One FSX Material = one drawcall, no matter how many textures are assigned to the FSX Material's slots.
As a perfect example of achieving draw call efficiency, consider one FS9 model (Eaglesoft's Liberty XL2) that I remapped/remodeled for full FSX compliance...
FS9 model had 384 drawcalls
FSX model has 15 drawcalls
In the process, I managed to double the texture resolution, reduce the texture loading (in spite of having more actual bitmaps!), and cut the framerate impact nearly in half. :ernae:
Most of that work involved rearranging the images more efficiently and actually using as many pixels on any single texture as possible.