A NIE is not something that Spanish citizens have. It’s a foreigner’s (to Spain) identity number. If you’re living in Spain you’d probably need one for many things like buying a car and stuff. If you’re just visiting then it’s going to be around 6 weeks to get one if you qualify
The technical rule is 20,000 baht or equivalent in cash only. Almost no one is asked for this. The only way they would ask is if they want to deny you entry based on extensive previous entry history
Your DTV is yours only. Your spouse may apply for their own DTV based on your having one, but it’ll be up to the embassy you apply at as to whether they’ll need their own funds to apply.
Check on their website for a list of requirements. I think if you have proof of stay in Taipei (like a hotel booking) they’ll allow you to apply there.
That is a well known consulate for being really tough to apply from. I doubt you’ll have any joy reporting to anyone. Go to Taipei or Jakarta. Both are pretty easy according to reports.