No, you do not need a special permit to use a chain saw.
No, you do not need a license to run a pole chain saw. In fact, most saws of these types can be bought at major home improvement stores and are safe to use as long as you follow the manufacturer's instructions.
they use a saw to cut large cunks of wood or metal
A chain sharpener is used for to sharpen a chain saw after heavy use. They need to be sharpened sometimes or they will not cut through material as efficiently.
Yes
If you have a ski mask and a mortician's apron, you can use the chain saw any time. The shrub trimmer, 9 a.m. to 9 p.m.
It can if you use it to, but the soil and stones around the roots will ruin the chain.
Chainsaw manufacturers recommend their own brand of chain for their chainsaws. However, you can use any brand as long as it fits or is made for your model.
Circular saws such as a K12 saw. Chain saws such as an Echo saw or a Tempest Ventmaster.
A chain saw sharpener can be used as often as you want. You could use it before and after each use if you wanted to. This probably wouldn't be necessary though. You should probably do so after ever 5 hours of use.
Just use a chain saw but get ready to sharpen it a lot
You need to use a tow strap not a chain.