Are there any functions or methods in smartsheet API 1.1 that allow you to create a new sheet or update an existing sheet based on an csv or xml file?
At this time the Smartsheet API does not have a method to import a CSV or XML File.
However, you can import the CSV in the Smartsheet application. More info here
Also, you can use a Java library to read the CSV or XML file and then issue the appropriate API calls to create a new sheet and insert the rows. This can be done more efficiently using the 2.0 version of the Smartsheet API.