Hi,
For managing new states and cities you can use e.g. custom tables and then display the values for custom document types using custom form controls which will pull data from the custom tables.
For the search filter and cascading drop downs you will need to develop custom web part which will have desired functionality andthen this web part will pass the filter values to the search which will perform the search according to entered criteria.
If you are looking for more complex and detailed proposal, you can use our
consulting services where you will get examples and best practices from our consultant how to develop this kind of web site (project).
Best regards,
Juraj Ondrus