First you should add a profile with your OS and your version of ArchiCAD since the answers you receive can depend on that information.
That said, the bracket is easy to create with slabs and then turn into an object or morph for positioning. Use the help files to learn how to do either of these operations. If you want an object for the bracket that is parametric, it will have to be scripted. I have attached a basic one for your use that was scripted in AC 16 (it will not work for lower versions).
The windows are a more complicated answer. You will not likely find a window that you can just put in that will look the way you want because most windows will be scripted and will need their parameters adjusted. However, once you adjust them for one window, you can use the parameter transfer methods to inject future windows and then you will only need to change sizes as necessary. If you have a special window that you can not create this way, you can create a window with building elements (walls, slabs, columns, beams, etc) face down in a floor plan (ideally at 0 elevation and at your origin) then save this as a window object. Again, the steps are in the help files.
HTH
Erich
AC 19 6006 & AC 20
Mac OS 10.11.5
15" Retina MacBook Pro 2.6
27" iMac Retina 5K
