yes, if you make another account
no, you can only do quests once. unless you make a new account.
Runescape is a free online role playing game. According to the Runescape information page, there are 23 free quests that a person may play. Members who choose to pay more may play an additional 165 quests.
For help on quests, try using the RuneScape Wiki
By tasks, you mean quests? Special quests would be only out on holidays.
These worlds are for runescape players to gather together to complete quests together. Some players might want to have some company when doing quests, these worlds (although not proven :p) might increase the chances that you find someone doing the same quest as you. Sone quests in Runescape require partners to finish the quests eg. Shield of Arrav, these worlds might make it more simpler to find a partner.
You find all the quests in the quest list, click on the quest tab.
no
The Smithing Quest
Dorics quest.
No.
LOts of quests offer money. Doing achievement diary also gives you money.