Is the need to answer security questions neccessary after trying to download stuff from a new computer?
NO! It's annoying and it's useless!
Forgotten Security Questions / Answers...
See Here > Apple ID: Contacting Apple for help with Apple ID account security
Ask to speak with the Account Security Team...
Or Email Here > Apple Support iTunes Store Contact
More Info > Apple ID: All about Apple ID security questions
Note:
You can only set up and/or change a Rescue Email Before you forget the questions/answers.