With the paraffin, my Grandma used to drop in a string and let it hang over the side till it had come to the top, this was to pull out the topping. I don't know anyone who uses it nowadays, most all of us use the 2 piece canning lids, which are cheap and very useful.
Simply follow the directions, thousands of women have made jams this way and succeeded. Just remember to tighten the lids and then set them upside down on a towel to cool. When they are cold, or room temp, turn them upright and push in on the round lid. If it goes click and up and down, it is not sealed. Either use it soon or process it again.
My sister and I had a firm rule..we wouldn't label it till it had set and we knew it was sealed. Then if it shook up like juice, we labeled it as "Pancake Syrup" and if it was solid, we'd label it "Jam or Jelly".