As far as I know, it is not possible to import a "simple" csv file into limesurvey.
Before there was a csv im- and export, but even then it was not as simple. Because somehow you have tell Limesurvey what it is importing and how to use it.
The only way I see at the moment for Limesurvey (and I would guess that its the same for any other survey tool out there free or comercial, if they even offer an import feature), that you will have to adapt to the format of the software somehow to tell the tool what you are pretending to do with your questions.
As I said, the only chance I see to do this is understand the .lss files (survey files are lss) and thus adapt your list accordingly.
Before there was a csv im- and export, but even then it was not as simple. Because somehow you have tell Limesurvey what it is importing and how to use it.
The only way I see at the moment for Limesurvey (and I would guess that its the same for any other survey tool out there free or comercial, if they even offer an import feature), that you will have to adapt to the format of the software somehow to tell the tool what you are pretending to do with your questions.
As I said, the only chance I see to do this is understand the .lss files (survey files are lss) and thus adapt your list accordingly.