Registration

I registered my brand new Dell laptop on this website: https://www.onlineregister.com/dell/?c=

However, I didn't receive any email to confirm my registration. Is this normal?

Secondly, someone told me that I can register my laptop somewhere and thus generate a list of the drivers it requires. Is this true? Are there other registration means out there?

Last, I accidentally posted my service tag on some forum. Can others who know the service tag use it to harm me or whatever?

Thanks:)