The first Helsinki contract offer was rejected by 98% of the HEL pilot group the second contract offer has been accepted by 98% of the HEL pilot group, its not perfect, but what is?
Not sure the contract period is relevant, either side can pull the plug at a months notice, I'm only aware of the company having exercised that option a couple of times and that was about the individual rather than the job position, i make no judgement on whether the company was in the right or not. I'm not aware of anybody not having their contract renewed.
If you want to join Norwegian then now is a good time as the recruitment will slow in 2015 when the last aircraft of the current 738 order are delivered, some of which will be to replaced the phased out 737-300's and a small number of early build 737-800 so no net recruitment.