I think it depends. If you payed over the internet,(PayPal, etc.) it should be instantly. If you payed by sending in actual money, it may take longer.
No, it does not matter if you are logged on to Runescape or not, it takes the same amount of time for your membership to credit.
Anything from 3 days to a whole week.
Once you subscribe for the membership, it will take 5 minutes at the absolute max.. usually it's instantly so basically there is no delay.
If you have paid by Paypal as a recurring payment then you can cancel it through Paypal - go into your Profile and you can find a list of recurring payments and cancel it from there.
I think you can't cancel a membership; you just have to wait for the membership to expire. In any case, check the RuneScape Web site, they may give additional information.
For life. a DA will never expire, i think runescape and world of Warcraft could take a leaf out of artix entertainments book with this
Once you have agreed to the membership terms, Jagex says it can take upto one hour for membership to become available. Although, in most cases membership is usually instantaneous.
It depends how long you are on Runescape.
You will find information on this reading a knowledge base article, I have posted a link for the page you want below in the "Related Links" section.
ajsajdiddm
Not that long, it's almost instant.