ad 1: I don't know if it's the best way, but when I so things like this, I just use a cube, subdivide several times and cut out the windows and doors.
ad 3: I don't use boolean very often (aka never :-) ), so it's better too copy a solution from a tutorial:
Blender boolean operations are done using the "Intersect" button.
1) Position two or more objects so that they overlap or intersect in space.
2) Select those objects with "shift+right mouse click" and (CTRL-J) join them.
3) In editmode (TAB), select all (A) then hit the "Intersect" button.
This will perform a boolean operation that creates all standard forms of booleans at one time. You must then select which parts you want to keep. This is done in editmode. You simply put your mouse over the area you want to select and press the "L" key on your keyboard. This will select all of the connected points on an object. You can then move, rearrange or delete any portion of the new objects created by the boolean intersect.
As far as I know they will remain as joined meshes so that they can only be manipulated independently in editmode with the "L" key. Use "P" seperate the selected verticies.
ad 2: Not sure about this point ... I think there was a way, but I have to try out later.
Believe me that Booleans are really the worst way to do doors, windows ect. and should be used only when it is really necesary (for example on rounded surfaces)- booleans are mostly unpredictable, need too much faces to perform, so it slows render and dificult later tweaking with proportions.
The really best way, experienced for all that years I am working with B., is that you find on pictures of that tutorial I have mentioned in my last post:) It is best becaus it is fast (faster then booleans) and it leaves nice meshes withouth unecessary polys completelly under your control.
And for booleans- there is no Intersection button in edit buttons anymore since 2.25. Now there are full booleans operations which you will find under "w" key out of edit mode