1) Pull down the File menu. Select Save A Copy As... select the Clone option and the copy will be empty of all data in all tables.
2) You can manually reset the next serial value in Field Options for each field or you can write a script that resets the next serial value using the Set Next Serial Value script step. But for fields used as primary keys in relationship, such is really not necessary to do. You can leave the values as they are after clearing the sample data from your file.