Miracle is just fine for growing in. Ive seen wonderful results with nothing but miracle grow potting soil, even without nutes. Your stretching is because you dont have enough light. if you can, try to put the highest output bulb on your flouro fixture, probalby 40 watts. adding bulbs is easy just get a powerstrip and some socket plugs and screw the lightbulbs into the powerstrip and youre good to go ( $20 for 2 powerstrips, 4 socket plugs and 4 23watt lightbulbs @ lowes ). and if you have to, stack some books or hang the fixture by some strings to get the plant closer to the light. Stretching is ok, but youre gonna have smaller nugs throughout your plant. the further apart your branches are vertically the smaller your buds will be, not to say the density will be less but just smaller buds. instead of having a few big nugs you will have a bunch of smaller nugs.
as for the mushrooms, just keep an eye out for more and use the bag method ( i used sandwich bags, the cheap ones without the ziplock on it ).
you should use tootpicks, wooden shishkabob skewers or even wire coat hangers instead of pens. washed or not, they can still leak ink and trace elements from the ink into your soil. if you're having problems with your stalk strength, you can help solve this by putting an oscillating fan on the plants. this will promote stronger stalk growth by constantly having a small breeze on them. my plants are 4 weeks from seed and the stalks are almost 1/2" thick.