If it is composted (well-aged) manure, than as already suggested mix the soil/ compost with a little manure (I'm thinking no more than about 70:30 soil to manure). If you are planting into pots, I'd mix in a little potting soil (or a little peat moss and vermiculite which are ingredients in potting soil) to lighten your mixture up. Be sure and put a little gravel or something in the bottom of your pots for drainage.
The straw is for mulch when you are planting in the ground; I'm about to do that for my strawberries. It's a little bit unwieldy to use for mulching your pots.
Scoobdoo was right, the earthworms are good. They will help break down the compost and manure into nutrients the plants can use. They will not eat your strawberries. Earthworms eat the decaying plant and animal material, including bacteria, in the soil.
Re how deep, are you talking about roots or plants? Either way it should have a little crown, which is the node where the stems start coming out. Be sure the crown is above ground. This article
midway down the page has a little picture of how it should look.