I would highly suggest using electrical string instead of tape. 2 reasons, the tape gets lots of abuse from the wind and sun. So IMO it wears out much faster than the string. 2nd reason is that the string is SO so SO easy to work with. Literally a pair of scissors and a few knots later, you're hot and ready to go.
I'll add a picture of the string I'm talking about, ignore the ice around it, that was from this past storm, but it's a really good pic of the string. Ice Storm 015.jpg
I have had to patch this string where the tractor got ahold of it on accident and broke it, it was as easy as tying 2 knots. I HIGHLY recommend it. I know the tape is sold because of it's high visibility...but horses aren't stupid. They saw this hot wire just fine.
We had about 1 acre fenced off with this hot wire. It did a great job. We used the plastic push in the ground type posts and 2 strands of wire. Never had a problem with it. After a while the horses didn't even test it. There were many days/weeks/months when we didn't even have it plugged in.
As far as how to break up the farm...I dunno. I do like the suggestion of the Arena being wooden posts with a top rail.....MUCH safer IMO.