Oracle DBA interview questions

How do you really prepare for technical questions you might get during an interview? I try to read as much as I can and review notes on basic questions or other typical interview questions regarding an Oracle DBA. On a recent job interview I was asked the following technical questions. I'll do my best to answer them as well, but if you have an opinion please fell free to chime in.

• How to you recover from block level corruption using RMAN?
• What is DBVerify and how do you use it?
• How do you dump your database to a file?
• How does export differ from datapump?
• How can you export and import an entire schema except for one table using datapump?
• A user has a SQL scripts that used to run in 1 hour and now takes 10 hours. The script has not changed. What could have caused this?
• What is the recommended time frame for gathering statistics in 10g and how is it done?