No. The flightless fly has no wings on which to fly. The winds on Kerguelen are strong enough that any flying animal would be blown out to sea.
you need to get money and buy a boat then you can go to the other islands
Not all islands have palm trees. The reason palm trees are able to grow on some islands is due to soil and the climate of the area.
You have to be more specific like what island. Then i might be able to help you.
tasmania,new zealand,tonga and the Fiji islands
Not regions seen in other games, but you can visit some islands that are introduced in the FireRed and LeafGreen games.
If you mean Horsea, then use any rod in Whirl Islands or Seafoam Islands and you should be able to catch it eventually.
you need to buy all of the stuff where its cheapest and sell i at the dearest islands then you will get money and be able to buy the biggest boat - eventually!
the divergent plate movement
Andaman and nikobar
Yes. People live there, so you could easily survive there.
How the flies would not be able to get in the jar
Simon