Q:

How can I import all emails and tagging from one gmail account into another?

It is easy to import the emails using pop etc?
However how do I import:

All my labels etc
My contact list

A:

Did you read the answers to your other question?
Per the link I gave in my answer to your other question:

If you absolutely need the old label structure, the only solution is to use an IMAP client to connect to both the old and new account and copy over folders/labels. But this solution can be tricky, because you can only copy over a certain (unspecified) amount of mail at a time. The non-Google program Gmail Backup might be able to assist with this process, but I can't vouch for its effectiveness.

Regarding contacts, from the same link:

Step 3: Export and import your contacts
  Login to the old account and follow the instructions on the Export Gmail contacts page. Remember the location of the saved file.
Login to the new account and follow the instructions on the Importing CSV files page using the file you just saved.

