It is a tutorial, it describes principles. It requires some extension on the part of the reader, not unusual for such.

There is a typo above, here is the page Basic Attachment Tutorial

After it worked through, I can answer any queries.

It's all in the tutorial, no point in repeating here.

No LCS.....

That old chestnut!

Works if started at the rectangle...... OS: Manjaro Linux (XFCE/xfce) Word size of FreeCAD: 64-bit Version: 0.22.0dev.36807 (Git) AppImage Build type: Release Branch: main Hash: cc96f2718e139d670e08c4226bdea9955a102ed6 Python 3.11.8, Qt 5.15.13, Coin 4.0.2, Vtk 9.2.6, OCC 7.7.2 Locale: English/Unite...

Great choice of file name ! I haven't got many of them!

Use the offset function in the tool......

Agree, the button should be shaded/different colour dependent on state.

3D CAD requires a little thought, a bit more and there can be a post at the end also.

I leave that to the student.

Select the last feature in the tree, and in the properties set Refine flag to true.

Why do you make things harder than they need to be?

Place the first sketch carefully around the origin, centred is usually the best, then use symmetry to advantage.