most of the type of wind turbines found here are directly connected to the battery bank. the charge controller also connects to the battery bank, and bleeds off excess juice to keep the battery voltage in check.
mppt wind turbine controllers are a whole different beast. even far different from solar mppt type devices. power curves must be programmed into them for correct operation, and voltage clippers are used in many installs. for a small mill, the cost would not be worth the gains.
honestly, i'd buy either a ts-45/60 or a ghurd controller. they will prevent overcharge from wind and or solar. the ghurd is great because it has limitless dump functions based on number of mosfets used, though it isn't temperature compensated. the ts-60 is temp comped, though spendier, but a great piece of electronics! i don't know what i would do without mine!
grounding: get one or two 8' x 5/8" coppers clad steel grounding rod(s). if soft soil, drive them straight in, at ten?? foot apart, if rocky soil, drive them at a 45 degree angle. basically get as much rod in the ground as you can. you can use a third, 4th or 5th rod if you feel like you can't drive them very deep. you can cut off what can't be driven, but sweat plenty with a sledge to get them as far as you can! acorn clamps are used to hook the bare #4 to them. don't worry about insulating the #4. it should never be close to any neutral or hot wire anyways!
adam