1. Yes, if you're buying a token, the token is redeemed on the account you wish you play.
2. Tokens are the same as paying $15 / month subscription.
3. You can still log into the account, even if it's inactive and play up until level 20.
3/4. You'll be prompted with an option on character select screen to purchase a game token (30 days) with gold and it'll automatically buy and activate account