If I am importing my current GMail id into another GMail id, and henceforth will use only the new GMail id then can I along with my emails also import all the Buzz and Chat details and contacts?
Can I import the emails from one email id to another by keeping the label structure and its associated settings ? So that my new GMail page looks "exactly" like my old page just that all emails sent to my old id will get redirected to the new GMail id.
This is easy. Gmail Backup should preserve your label structure in its backup. Just back up your account with it and then restore the backup to the new account.
IIRC, this should take your buzz and chat with you, since they are stored as messages. However, I don't think transplanting the Buzz messages will do anything.
And then you can forward all the new email.