Hi,
Will be flying SIN-MCO on BA/AA with route as follows :

SIN-LHR on BA metal
LHR-MIA on BA metal
MIA-MCO on AA metal

All flights booked on a single itinerary and group all holding Singapore passport which has Visa Waiver with USA.

Have a couple of questions :
1) Will our bags be checked through to MCO or will we have to retrieve them at MIA, clear CBP and re-check them into AA ?

2) If we have to clear CBP at MIA, and re-check bags with AA, would a 1hr 39 min connection be doable realistically ?

3) Given that all flights are booked on a single flight locator, would it be prudent to assume that should we miss the connection, AA will re-book us on the next flight out from MIA to MCO without additional costs ?

Thanks for response.