Ask Marc for a copy of his manual - covers all aspects of growing.
From what I have read so far, osmotic shock is a reasonable good way of extracting oil. I have not got to trying it yet but will soon.
I will be partially dewatering the harvested cells by either centrifuge or just drip drying, and then dropping it all straight into a tank of distilled water. Hopefully the oil will float to the surface and the dead cells to the bottom, making getting the oil easy.
Let us know how you do.