Welcome to FT londoner2004
1.I think that you are still only allowed 2 pieces as a FTL, phone check-in can be done 24h before the flight
2.If I remember right you can take 2 pieces of luggage and if they are not too heavy I do not think that the CIA is going to charge you for them. I had a similar situation 2-3 months back when I flew IAD-FRA with 4 pieces in economy. The CIA only charged me for 1 though, because the other two were not that heavy.
It is really hard to give a definitive answer on this it really depends on the CIA that you get, if it is only the weight they will most likely not charge you for anything.
You can take 2 pieces of handluggage, 1 laptop + something else.