Hi Chuncui,
To answer your first question, we have a more recent version of StreetMap Premium USA TomTom 2014 Release 1 shipping, that is almost a year newer than the version you're referencing. As Esri is continuously improving the locators to provide users with better match rates, you should use the latest locators that are delivered in the 2014 release 1 version. If you're current on the maintenance (if you've renewed the StreetMap Premium product), you should automatically receive these updates; if not, then you are likely not licensed to use these locators indefinitely. You can also cleanse your addresses by using services offered by providers such as Loqate and Trillium. Cleansing addresses does not guarantee that you'll get better match rates as that depends on many factors. You can also try to interactively rematch the unmatched addresses using the interactive rematch tool.
To answer your second question, Esri is not combining the Census TIGER reference data with the commercial, TomTom reference data to build these locators included with StreetMap Premium. However, you may build your own TIGER based locators and create a composite locator that combines the commercial-based StreetMap Premium locators with your TIGER based locators. Again, this does not guarantee that you will get more precise results and improve your match rates as the commercial data is already comprehensive in currency, coverage and accuracy as compared to the TIGER data, but you can try.
Our recommendation is that you would use the latest TomTom locators in the current version of StreetMap Premium USA TomTom 2014 Release, which are based on more current vintage of the TomTom reference data.