yes.
Anything in a cell that provides a function for the cell is an organelle. If it is just there temporarily, like food, than it is not an organelle.
I am not exactly sure, but i think organelles made when a cell is made, or reproduced. Organelles are a nesscesity of cells and just come when a cell is made.
it is the nucleus.
Mitochondria, is the Powerhouse of the cell