Speak to Steven in Silph co. after you have collected all 16 badges. (You will only be able to get one, you will need to migrate the others)
Speak to Steven in the Kanto's sixth gym city after you collect all 16 badges.
In the begining of the game, you can choose between todadile, chikorita, or cyndaquil. After you beat red, talk to professor oak to get a kanto starter, and steven to get a hoen starter.
Torchic, Mudkip, and Treeco
you just train your newly obtained starters and battle the elite 4 and Red again
to get the hoen starters get the 16 badges then go to the silph co. then you will see steven and he asks you what color rock you pick.then you get one of them. green=treecko blue=mudkip red=torchic
You can only reach Kanto and Johto.
The Starters are Cyndaquil, Totodile and Chikorita
you can't. Pokemon heartgold and soulsilver versions only have two regions: johto and kanto.
You can't go to Hoen in soul silver.
You cannot actually go to Hoenn in SoulSilver, but you can catch Pokemon from Hoenn on Wednesdays with Hoenn Music on the radio.
By Ruby I'm assuming you mean the Hoenn starters, then yes, you can get one of three of them in HeartGold/SoulSilver
no, you can only go there in emerald, sapphire, or ruby
Steven is in Silph Co. in Saffron city