(1) Regarding your solution, not clear how to work, but regarding TPS2511, please note that it integrate 3 modes (divider 2, 1.2V on D+/D- and shorted mode), default mode is divider 2, when plug in one BC1.2 device, TPS2511 will switch to BC1.2 mode, when plug out the device, TPS2511 must back to default mode, the switching need take some time and different device would case different behavior.
(2) Yes, you can use TPS2546 load detection (/STATUS), set a detection threshold (for example 100mA), when charging current exceed 100mA, /STATUS output low and indicate that have device plug in, when charging current lower then 100mA-hysteresis, /STATUS output high, indicate device plug out, but it can't distinguish fully charged and plug out, because the fully charged charging current lis very low.
(3) Also, there is special USB Type A receptacle that an optional contact is added to the Standard-A connectors to allow insertion detect.