Question Regarding Character Trading / Purchasing

There's a character I'm looking to purchase on the website. But I had two questions regarding it.

- Is the process of purchasing a character instant? Will the character be on my account immediately after purchase or do I need to wait some time for it to take effect?
- Do I need a premium account to purchase characters? I read mentions of a premium account being needed for character trading but I couldn't tell if it was for selling, purchasing or both.

Thanks!