I was booked on Iberia to fly FRA-MAD-MVD this coming Thursday. While checking my seat assignment online, I noticed that the MAD-MVD flight no longer operates Thursdays. The only involuntary re-route that fits my travel plans is now FRA-MAD on the same flight as originally scheduled, then one hour less layover in MAD (fine by me) and taking the MAD-GRU flight (which is shorter, so less time on board, also good!), but then I arrive at 7:55 am and must leave at 9:15 am on a TAM flight to MVD. Also, Iberia cannot confirm seat reservations for the trans-atlantic flight nor for the TAM flight, so maybe they are overbooked. Several questions arise:

1) assuming I make all my connections, will I be denied AAdvantage miles for the GRU-MVD segment because TAM is not a oneworld partner?

2) do I need to take my bags through Brazilian customs, and do I need to go through immigration and/or security? (I am an EU citizen, so I don't need a visa)

3) if I miss the TAM flight to MVD, the next flight is with Gol, which would get me into MVD more than four hours later than my originally scheduled arrival--does that mean I am entitled to compensation according to Article 7 of the EU Regulation 261/2004 regarding flight cancellation, since I only found out about the cancellation today (on my own initiative)?

4) what if I am denied boarding to either of the two connecting flights?