Yes, look in online catalog, 1/2" and 5/8" are available.
Yes, as long as they are hammered all the way in. Make sure you have fencing plier just in case you have to extract one
No . You may need to look into more secure ways you walk your line .
Unknown, call Grip Right, the manufacturer. I have used these for securing electrical wire but you must be careful, they can cut right through a cable or wire if driven too far.
Mine had about 40-50
these are for hammering in using a hammer but use caution and wear gloves ....you will strike you thumb nail often