I can only help with your fence part of the question. Between 6-8 weeks old (depending on size)
You might consider letting them free range if you don't want a permanent structure. They learn in about 3 days that just before dark they go back to their indoor living. They are very smart. I let my
Flock of 30 out every A.M. And leave the door open to their indoor spot (they know it is their safety
Spot, and will go in if they sense danger) they have 9 acres to free range, if you have a field let it grow high w/weeds, grass, it provides great cover for them while they are young. At first they stick pretty close to their safe spot, but they love to graze, chase bugs, and interact. They do not like extreme direct heat and need shade, & lots of fresh cold water in the heat. Within 2 weeks your birds
Will be right by their indoor spot when it's close to dark. I started from day 1 with clapping my hands
As I was pushing them towards their indoor spot. Now I just clap & they literally run in, it's so cute
And shows that they really are very smart. That is for sure a very dumb old wives tale that says Turkeys are dumb and can drown in the rain. They are fun to raise, very social. I enjoy them more then chickens. I hope this helped.