I would forward all mail received during that period to a trusted friend or family member who can let you know if you receive correspondence from USCIS. Missing a scheduled interview would not be wise.
The immigration process requires a great deal of knowledge, planning, time, patience, and money. Becoming an A student of the process is a good first step. Good luck.
"They have transformed the nation that was once known as the leader of the free world into a crime-ridden, open-borders free-for-all where opponents of the regime are arrested on bogus charges. "
I-864 is not needed for a K-1 visa. I suggest you study this guide:
K1 Fiance Visa Step-by-Step Guide on Filing an I-129F for a Foreign Fiance - US Immigration & Visa Guides - VisaJourney
Not sure what you mean by that, but marriage to you confers no immigration right, nor does an I-130. Once an I-485 is filed, she cannot leave the US without abandoning her I-485...unless she has an approved advance parole document in hand.
Unless your employment will continue after you re-locate to the US, an employment letter is useless and not needed. You can claim only income which will continue after re-locating. Unless you can show sufficient assets or sufficient current income which will continue, you will need a joint sponsor.
LONG LIVE TAIWAN!!!!!!