1. No you must have a data plan to get email sent automatically to your phone
2. You lose email being always there, web being always there, and no BlackBerry Messenger and third party applications. Those all require the data plan
3. Full pages will run slow even if your on a wifi connection or the data connection. It's the fact of the phone rendering the page. I recommend using the mobile version as much as you can so it loads faster unless you really need the full version personally.
4. Go to m.youtube.com for youtube