I'm considering booking LHR-MAD-DFW (rather than LHR-DFW) in December as I can clear a SWU now on the MAD-DFW leg. I've never connected through the EU before so a few basic questions:

1. As it's a single itinerary booking, will I have to collect and recheck a bag in MAD? LHR-MAD will be on BA, MAD-DFW on AA, both flights look to operate out of T4S.
2. I'm assuming I will have to go through passport control. Will I have to go back through security again too?
3. About how long should I allow for the connection process? There are 2 flights I can choose from LHR. One with a 2:55 connection and the other with 1:40.