You are always in Sinnoh.
You have to see all the Pokemon in Shinnoh. (You do not have to beat the Elite 4)
You can't.
Rowan gave you a pokedex for a reason
For Shinnoh:493 Isshu:649
The next series is called pokemon black and white
transfer the Pokemon from gba game into pal park and capture
no, not necessarily, you do however need the nationalDex which you get for seeing all 150 Pokemon in shinnoh
find em all stupid
you go to moon island and see cresselia but it will run away so you have to search all over the shinnoh region to find it and it will sometimes randomly appear when that happens it will run on its first turn just like mesprit.its a real pain.
This is how you get the Pokemon radar. First once you defeat the Pokemon champion and you see all the Pokemon in shinnoh you go to profecer Rowan and then you talk to him then he will gove you the Pokemon radar.
Probably, it doesn't seem as though there will be any further games after Platinum
there is no possible way of catching piplup chimpchar or turtwig in heartgold or soul silver, you would have to trade it wirelessly or by wifi from pearl diamond or plantinum. Hope i helped enjoy the world of Pokemon peeps. Not to make you sad but its spelt Sinnoh xx