First suggestion - you're exposed to Air Flow Control four times? Doable, and probably less AFC in March than any other month in the year, but still urgggh...
Your second suggestion is not legal - you just void all remaining segments on your earlybird ticket.
Can TPE be substituted for PVG? More predictable landing times and a shorter detour
P.S. first suggestion - you're gonna need multiple reentry visa, not your normal business visa.