Runescape has around 144 worlds, free worlds and member worlds. Runescape 1 is the same as Runescape 2, so Runescape 1 gold works for Runescape 2 without any problems. The RS Gold you buy from any of the worlds will work for all other worlds, since the Gold stick with your character, and not with the world itself.
From my knowledge, most of the MMORPG currency shop's RS Gold is farmed by Chinese, Romanians, Indians and Americans. It really doesn't matter who farm the gold, the most important is the method they use to farm the gold.
Some farmers are using macro bots to farm the gold, which will end up with a ban; some are killing dragons which is a safer method to farm the gold. But as far as I know, the Runescape GM will not ban the buyer, they only ban the seller, thus as a customer, you really don't have to worry much about it. Basically, after you placed an order in a MMORPG currency shop, they will meet you in a chosen world and do a face to face gold trade with you.
You can also trade in online sites, people always like cheap price, online Sell RS Gold sites can satisfy you.