Cut yourself 2 dozen pegs, and practice, you may find you need ten, you'll probably find you need a few less, its what suits yourself. The rest you will always have for when you loose one or maybe break one.
As for nets, its a personal choice thing, 2 x 25yards would be easier to work, but more pins, possibly more pegs as well.
If it was me, I would go for 2 x 50 yards and practice a lot in the day time hours, if you find them awkward you can cut them down
Dont be concerned about 4z - Its not too light for you, it will lift a little more nonsense from the ground, but the lighter w