How to Rotate Selection and Draw Shapes?

[Blighty]

(04-23-2018, 06:12 AM)TechnicGeek Wrote: How to rotate selection, be it custom or rectangle or circular?

Select the Rotate Tool. Then, in the Tool Options, set the Mode to Selection (see attached)

Quote:How to easily draw ready shapes, like rectangle and circle? I haven't found them in the toolbox.

I suspect you are thinking in vector graphics terms (eg Inkscape). It has rectangle and circle objects.
For a bitmap editor like Gimp, it is a little different.
Create a selection, then Edit > Stroke Selection
(or better, create a path and Edit > Stroke Path