new member, please give me alittle advice, thanks

Hey, I am planting about 60 seeds in the ground. I was going to make about 6 different spots with 10 seeds in each (each strain of green has its own spot). I was going to dig a whole about 3 feet deep, and im not sure how wide yet (any suggestions for 10 plants - how much room they need?). What should i do in regards to soil. give me a conrete, easy soil mix that will work well. I have heard that mixing potting soil, perlite and come compost to be a good one, but im not sure of how much of each part. Also, can someone explain fertilizing to me. When should it be done? with what fertilizer? i really need some help as my season starts soon. What brands if soil do you guys like for outdoor growing? How much green would think 60 outdoor plants would yeild? take a guess? I really appreciate any help, really. Thanks alot.