No. When you import data, a new survey is created automatically. All questions and answers are also created as per the imported file format.
Yes. You can edit the survey, change the text for questions and answers. However, we recommend that you don't make any structural changes. If you make structural changes the data may get affected.
Every time you import data a new survey is created and the data is imported in the new survey. Data cannot be imported in to an existing survey even if the survey was created importing data in the same format. Please maintain the data file that you used to import data offline. To add more responses please add data to the same file and import the data again. A new survey will be created that will have the entire data.
Data can be imported from an excel (.xls) file format. First twenty six columns are reserved for system variables including some important data columns. Actual survey questions start from the 27th column (I) onwards.
Below is the list of supported question types to "Import External Data Into Existing Survey"
This feature/tools described here are available with the following license(s) :