Serious questions.
1) What happens if you dig down?... How thick is this supposed "Flat" Earth?
2) How come when you dig down, The earth gets warmer? Since it's flat I assume the large surface area would be large enough to dissipate any heat created by friction.
3) How do Communications and navigational satellites orbit?
1) We're not sure, but based on the depth of the Marianas Trench, something more than 20 miles, probably significantly more.
2) I see no reason to assume that. I see no reason to not think that the lower layers of the earth are under enormous pressure, thus leading to heat.
3) They don't exist (except possibly as stratalites).