a bios update is never something that you HAVE to do when upgrading the cpu, although at times, you should.
in this case, pcpartpicker says that you may need to update it.
for your second question, it is not dangerous in the sense that your components will stop working or anything serious like that, but rather there is a slight risk of you losing all of your data. just make sure you've backed up your data and you should be fine.