Feel free to msg me in advance of your next trip to SH, and I'll be happy to attempt to help. I will note that is very hard for US citizens to get HSBC accounts in China/HK, but this is seemingly a good option if it works.

WRT sim cards, in the past I encouraged people to buy them in electronics markets or on the street, but the real name registration thing will bite you sooner or later (especially when setting up Wechat Wallet/Alipay). As such, find a Unicom store that isn't busy, and get one of their lowest priced prepaid plans; adding money (for talk time and/or data) is cheap and easy with Wechat (and, your foreign CC will work).

ETA: A lot of my friends use China Mobile because coverage tends to be better in 2nd/3rd tier cities, but I've been with Unicom for the past 5 years, and don't have any complaints. It also costs a little (i.e. trivial amount) less.