Hi,
I am not quite sure about China. Yet cases temples or shrines in Japan, sandals are OK, T-shirt is OK, but care about to cover your sholder, skirt is also available, but do not choose short one
pants is safer, I am sure, if you don't show your thighs.
Socks, you might come to Asia at Summer, mightn't you? It is already humitted. When I wear shoes, I also wear hemp socks to keep my feet comfortable
have a nice trip!
Reikkonen