Best of luck on your first extraction.
I also haven't done this just as of yet, but will soon. I read a few times that the seperatory funnel is well worth the investment, so Iam looking to purchase one as well. Found a couple gallon glass jars for free as well.
What size of trays are you using for your mushroom grow?
I much prefer to spawn grains to a bulk substrate and only apply casing layers if it is a project that will be neglected some. For a bulk substrate I mix either coco-coir or horse manure (horse manure has a better consistency than cow manure) with some vermiculite, gypsum, and just about %5 total volume of composted chicken manure(not too much of this stuff). You actually want to stay away from overly-nutritious bulk substrates when cultivating cubensis, but the above mix has served me very, very well.
arrive without traveling.