Wow, good question. How’d you let your passport expire!??
My hunch is no, definitely flying wise. If you’re doing trains within the continent the only issue would be if you get caught by the police and some hotels might not go for it…
Why not talk to your consulate/embassy and see if they can arrange a passport for you quick?
No, you need your passport! I tried to get into Gibraltar with only my NIE and they wouldn’t let me (luckily I was just checking to see if I could and I had my passport with me). Good luck!