I have few very basic doubts in Autodesk Revit regarding drafting (drawing) ?

[Anonymous]

1. While drawing Floor / roof, should the sketch lines be inside the external wall or should it be extended till the outside of the external wall. 

2. Should the external wall be extended till total height of the building (to avoid breaks in between), or drawn at every floor level.

3. How to use 'At Grids' command in Architectural columns, (Its visible in structural columns but not showing up in Architectural columns) 

[L.Maas]

1. Depends on how everything is going to be build. But from Revit standpoint both options are possible

2. Depends on how everything is going to be build. But from Revit standpoint both options are possible

3. Some functions are only available for certain elements. Indeed "at grids" is only available for structural columns.

A good rule for Revit is. Create the model in a similar way as it will be build in real life. So if the building will be based on multilevel walls I would do the same in Revit.