The only minimum is to be 1000ft away from crowded areas. Other than that they simply need to fly safely, see and avoid other traffic, and if in controlled airspace, comply with ATC instructions.
Fly. Actually seaplanes do both and can take off and land from the water.
I think that it depends on how long is your kite string is .
Seair Seaplanes was created in 1980.
I think planes can't do that, because they would simply sink slowly.
Loch Lomond Seaplanes was created in 2007.
Palm Beach Seaplanes was created in 1995.
Seaplanes are on sale from many different stores and retailers. Some examples of stores that have seaplanes for sale include Seaplane Market and Aerotrader.
You can legally fly a nitro airplane in the United States. The recommendation is to fly with membership of the AMA (Academy of Model Aeronatics), www.modelaircraft.org
Not legally.
The 757 has a service ceiling of 42,000ft so it is legally capable of flying at any altitude up to 42,000ft
High
Seaplanes can be used to access remote areas that are surrounded by water. E.G. Islands, remote parts with rivers and even ships.