I have just left the Mainland for the day, sorry for my late reply but Flyertalk takes ages to load in China...if it is not blocked by cloudflare that is.

I would not worry at all about the 15 day visa free being an issue in two weeks time anymore.

If you do not have an E-SIM ready smartphone, order a Travel-Sim card for China to have WiFi for Alipay/Weixin Pay.

Have been lucky twice with ICBC and ABC Bank ATM accepting my Curve Card, but I would not count on finding an ATM everywhere.

​​​​​​I have travelled CKG-HGH-SJW-FOC-ZUH train to Shenzen-SZX-FOC ...and just left FOC for TPE, before returning to CKG and back to BUD tonight. Zero issues.

My biggest "issue" by far in every Hotel, train station, Airport, even the ultra friendly immgration officer in FOC today took four attempts to find it - before I told her the page number - etc. was the entry stamp ink was/is barely visible...and exactly placed on the AUSTRIA watermark in the passport. The stamp that I left China today next to it in comparison is visible from a mile.