Correct, no insulators needed for that style step-in post. They will hold up to 2" tape or wire. I also like them because their ends are capped with a top insulator, reducing the chance that someone might impale themselves. They also make plastic-coated metal step-in posts that do not need insulators, either.
The only downside to step-in posts is if your pasture is exceptionally rocky, you may have problems getting them in the ground.
I can’t answer the charger question-- I honestly have no clue, and it will depend on how much fenceline you are talking about. I have one of these which I bought for nearly 50% off at my local feed store. It works fine for my little 5 acre farm!
You can use tape splicers to connect tape. You just need to make sure to get the correct size. This is going to sound pretty unprofessional and sloppy, but tape is easy to work with-- even worst case scenario, you can tie ends together.
I bought a bag of plastic tensioners wide enough to accommodate tape at my local feed store. I can’t seem to find a link for them online. Depending on the size and shape of the fence you’re creating, you may just be able to pull the tape tight.
I am clueless about the zigzag pattern, though! I just have a vertical strand of wire (same type of metal) between my fence strands to energize them. That’s probably not how a professional would do it. :lol:
Also, invest in an electric fence tester if you don’t already have one-- even the cheap $10-15 light up style is sufficient. It takes the guesswork out of installing the fence and knowing if it is working!