When you ask a question on the forum you should post your machine and software version or some bully might kick you off. I assume you are V10.
The general tone of your questions means that you need to do the tutorial and read the manual because you will encounter numerous minor problems like these if you continue to try to wing it. There was a time when one could do this in Archicad, but not since about 1997 when the program grew beyond intuition.
Wall on line: The "magic wand" tool converts linear elements into 3D elements. See Reference manual for many references. Activate wall tool - place cursor on line, Space Bar Click. Voom. A wall on the line. See magic wand settings for tolerances.
Lineweight: Set On Screen View Options to "True Line Weight."
Wall composition: You create composite walls according to their construction using the Composite wall tool. Or you make a generic fill, or you assign an appropriate surface material. Big issue for a new guy.....
Line by keyboard: Archicad can draw like Autocad does, more-or-less. See the training guide. It is an essay to explain but thirty seconds to demonstrate.
Curved windows: It is easiest to emulate curved windows with a curved glass wall, but there is a curved window in the library: WM curved 10.
Timber details: Do you mean log walls or heavy timber? That is a complex question since there are many ways to model timbers and Add-Ons to facilitate this - Framewright, for instance. But you CAN detail this.
Dwight Atkinson