Guess you know the answer by now....less than 45 mins all done 😊😊😊

Probably not. They have opening hours.

地址： 112台北市北投區溫泉路 電話：02 8733 5678 營業時間： 今日正常營業 · 09:00–17:00

It's a district - there's no telephone number as far as I know from my last visit. I trust, the cheap unisex public one - no need reservation but the rest of the area the thermal onsens are offered in the hotels in the area, you can try to google one of the resort to check. Gentle reminders: those onsens are male - female separated and you need to be totally naked to use the facilities - please check before you enter or pay your fee that the facilities require bathing wear or else. Some place also doesn't provide towels better to carry one with you or prepare to pay for rental or purchase a few.