Where is the endoplasmic reticulum found within the cell?

Which organelle is responsible for the synthesis of proteins that are involved in the structure of lysosomes and the plasma membrane?

The double-membrane,sac-like tubular structures found in the endoplasmic reticulum are known as:

Nuclear envelope is a derivative of

Rough Endoplasmic Reticulum $(RER)$ $= ..........P.............$
Smooth Endoplasmic Reticulum $(SER)$ $= ......Q...........$
What substances do the above Endoplasmic Reticula synthesize/secrete respectively?

What is the function of the smooth endoplasmic reticulum $(SER)$?