When a drawing is done to scale, you should label it with its dimensions.
Use dimension lines to label each dimension, with extensions where necessary
You should label just enough edges to show all the dimensions, but you don’t need to repeat.
In Canada (at least for science) dimensions are usually given in millimetres (mm). If you use different units (cm, in, feet etc.) you need to write the unit. You do not need to write mm if all of your dimensions are in millimetres.
Angles can be shown in degrees (°), diameter by Ø, and radius by R