I agree with Robert, you have done a great job so far as it really quite a complex project!
First I thought I would just answer your question on Locations. Basically you have really got the idea of them, as you have a Foundation, Ground and Second Floor - these are Locations but as Robert suggested you need one for the garage and in fact you need a separate location for every floor level and wall height.
The Location basically control your third dimension, they will control all the vertical distances, so need to be set correctly to start with or you will have problems later on. Usually rooms in a building that have different height walls or a floor that is a different height above (or below) the ground, should be on a different Location, with its own specific vertical measurements.
Locations work like this (using typical dimensions to illustrate the Wall Heights and Floor Levels [top surface of the floor]).
1.) Terrain is Zero (and the various levels are calculated from there)
2.) The Floor Level for your foundation Floor would be minus 8' as it is 8 ' below the terrain (presumably).
3.) The Foundation walls are 8'.
4.) The Ground floor is 1' thick (by default) and sits on top of the foundation walls but has now gone above the terrain by 1' so the Floor Level of the Ground Floor Location is 1'
5.) The Ground floor has 8' walls
6.) On top of the walls is the 1' thick floor for the Second Floor, so the Floor Level for the Second Floor Location is 9' above the terrain.
7.) The Second Floor walls could be a very different matter if the ceiling slopes and is lower than 8' at the edges. So... how high is the lowest VERTICAL part? If the ceiling slopes right to the floor, then the VERTICAL wall height should be set to 1 inch for example or less (turn off the baseboard in this case) and the ceiling height should be the same. If the VERTICAL part is 2' then that is the Wall Height for the Second Floor Location should be set to 2'. The Head Height (door height - 6'8") should remain the same as the head height for the other floors. Make sure that the walls are set to 'Extend to Roof' so, although they are only 1" high (or 2' high) when you draw them, they will extend to the roof, so you can still insert doors and windows.
8.) If you have another level in the home, eg, the garage is 2' lower than the foundation floor, then create a new Location as Robert suggested, called Garage for example and so the floor level for the garage would be -10', with 2' walls and 6'8" Head height. If it has a separate ceiling then it should be set to 10' or whatever height it is above the garage floor.
As far as your existing Locations are concerned there is not a lot wrong. If the foundation is below ground level, then the easiest fix is to move the Terrrain up by 8' (or whatever the distance is- Settings/ Programme Settings / Terrain) and leave the existing Foundation and Ground Floor Levels as they are (ground at 9'). If you are really adventurous you could slope the terrain so that it matches the real thing.
The Second Floor Floor Level however may not be right. If the Ground Floor walls are 8' then the Floor Level for the Second floor should be 18' - if this floor is also 1' thick (8' Foundation walls + 1' floor thickness + 8' Ground Floor walls + 1' floor = 18' above zero). If the Second Floor does not sit on top of the ground floor but is lower, then it may be in the right place at 15'1 1/2". If you leave the Foundation at zero, then make the new garage location -2' (or whatever the correct measurement is).
I hope that clarifies the Locations for you (or does it confuse it?
When it comes to the roof it sits on top of the walls of the location where it is inserted. So the roof should be inserted on each location that has the highest walls above the terrain. Obviously you do not insert a roof on the Foundation location as it does not go to the roof. The ground floor MAY go to the roof IF the second floor does not cover the whole of the building. In this case the roof would be on two locations, the Ground Floor and the Second floor - by default the second floor would cause the ground floor roof to dissappear where it is overlapped by the second floor roof. Does that make sense?
If you don't get it all please ask again.
By the way, you will find TurboCAD is MUCH more complex that TFP. I gave up with it - too big a learning curve for me at my age I'm afraid - haven't got the time, or the patience anymore!