Will it be possible to import notes from HM2 NC to HM3 NC?

As the title says....=)

Yes, this is already possible :) You need to export them from HM2 NC (you can do this by selecting the notes you want to export, right-click on them and choose Export) and then import them into HM3 NC (by going to Tools / Import / Import Note Definitions and select the ones you want to import).