Xiamen visa free transit

My husband and I have a ticket from XMN to Amsterdam, flying on 5 June. We will be visiting friends in Hong Kong and plan to fly from HKG to XMN on separate tickets (3 jun or 4 jun with CX or Xiamen airlines) to catch our flight on 5 June. We are both Dutch passport holders. May I know how long it takes to get the transit visa at airport? When I board the flight from HKG, do i need to inform the airline that we will make use of the 144 hours visa free transit? And in case if we visit Tulou area, is it still counted as XM? Thanks a lot!