You start out in the johto league and you work there till you've beaten its league then you go to can go to the other regions(except for sinnoh)
It depends on if you choose cyndaquil for your starter Pokemon in the johto region. If not your rivel (Heart) might have it.
As far as I know, the Sinnoh region is not included in Soul Silver.
you cant
No it's the Johto region
You can't go to the sinnoh region.
Yes there is.
Just like the regular Pokemon In Kanto.
You have two beat the Pokemon league.
No, In Pokemon Diamond & Pearl you can choose Lucas or Dawn and travel through Sinnoh Region, But in Heart Gold & Soul Silver you can choose Ethan or Lyra and travel through Johto and Kanto.
they are spread through out the region
yes
cyndaquil, chikorita, and totodile