Ok, in my quest for a more fulfilling simming experience (ful-filling with trees, ful-filling with buildings etc...LOL), I decided to try my hand at using the FS9 autogen SDK.  Near the bottom of the word document that won't open with converted images (thank you VERY much MS) it talks about the limitations of the sim's autogen process.

It states:
"the scenery engine in Flight Simulator limits the number of buildings displayed to 300 per square kilometer and the pieces of vegetation displayed to 600 per square kilometer. "

One of the many questions I had about this, I have answered already.
1) What happens if I use the annotator tool to add more than the sim can render? (I found the answer to this the hard way) The sim crashes while loading the scenery.

These are a little trickier, and I could use some help from the experts.
2) How do you mearure one square kilometer in the sim?

And
3) Once you know how large an area one km is in the sim, how do you determine which scenery textures are going to be used there?

Now I know that certain textures are used in specific areas, and that those textures are named (or more accurately, numbered).

For example, the table below describes it all:

Land Class Number      Description        
004B2      Crops (Default Region)        
004c2      Crops (Red Desert Region)        
004h2      Crops (Tropical Region)        
005A2      Non Geometric Crop (European Region)        
005b2      Non Geometric Crop (Default Region)        
005c2      Non Geometric Crop (Red Desert Region)        
005h2      Non Geometric Crop (Tropical Region)        
007B2      Geometric Crop And Town (Default Region)        
007h2      Geometric Crop And Town (Tropical Region)        
008A2      Non Geometric Crop And Town  (European Region)        
008B2      Non Geometric Crop And Town (Default Region)        
008F2      Non Geometric Crop And Town (Asian Region)        
008h2      Non Geometric Crop And Town (Tropical Region)        
010A2      Grass Crop Shrub  (European Region)        
010B2      Grass Crop Shrub (Default Region)        
010F2      Grass Crop Shrub (Asian Region)        
015F2      Rice Paddy (Asian Region)        
029B2      Large City Urban Grid Wet (Default Region)        
029h2      Large City Urban Grid Wet (Tropical Region)        
030B2      Large City Urban Grid Dry (Default Region)        
031B2      Large City Urban Non Grid Wet (Default Region)        
031F2      Large City Urban Non Grid Wet (Asian Region)        
031h2      Large City Urban Non Grid Wet (Tropical Region)        
032B2      Large City Urban Non Grid Dry (Default Region)        
033B2      Medium City Urban Grid Wet (Default Region)        
033h2      Medium City Urban Grid Wet (Tropical Region)        
034B2      Medium City Urban Grid Dry (Default Region)        
035B2      Medium City Urban Non Grid Wet (Default Region)        
035F2      Medium City Urban Non Grid Wet (Asian Region)        
035h2      Medium City Urban Non Grid Wet (Tropical Region)        
036B2      Medium City Urban Non Grid Dry (Default Region)        
037B2      Large City Suburban Grid Wet (Default Region)        
037h2      Large City Suburban Grid Wet (Tropical Region)        
038B2      Large City Suburban Grid Dry (Default Region)        
039B2      Large City Suburban Non Grid Wet (Default Region)        
039F2      Large City Suburban Non Grid Wet (Asian Region)        
039h2      Large City Suburban Non Grid Wet (Tropical Region)        
040B2      Large City Suburban Non Grid Dry (Default Region)        
040F2      Large City Suburban Non Grid Dry (Asian Region)        
040j2      Large City Suburban Non Grid Dry (Middle Eastern Region)        
041B2      Medium City Suburban Grid Wet (Default Region)        
041h2      Medium City Suburban Grid Wet (Tropical Region)        
045B2      Small City Suburban Grid Wet (Default Region)        
045h2      Small City Suburban Grid Wet (Tropical Region)        
046B2      Small City Suburban Grid Dry (Default Region)        
047B2      Small City Suburban Non Grid Wet (Default Region)        
047F2      Small City Suburban Non Grid Wet (Asian Region)        
047h2      Small City Suburban Non Grid Wet (Tropical Region)        
049B2      Large City Highrise (Default Region)        
049h2      Large City Highrise (Tropical Region)        
068b2      Dry Crop (Default Region)        
069b2      Dry Crop and Town (Default Region)      

BUT, to keep the scenery "fresh", and from looking like it was placed with a cookie cutter, the sim uses an ever changing blend of various default texture sets, and mixes them up in a seemingly infinite pattern.

So do I simply guess as to how many trees or buildings to place on each texture tile, and hope I don't go over the 300, or 600 unit limit? The annotator tool does keep count of how many objects you have placed (or areas as it applies to vegitation), but that doesn't tell you how many there will be in one square km after the different texture tiles are butted up next to one another. Has anyone found a safe max number of units each texture can have?

Anyone?