Thanks for this information!Just a quick heads up: Messiah Complex can be read on its own. It was my first modern X Crossover event and I still love it until today. Many criticize the event for a shift towards the more "cinematic" storytelling but in my opinion they tend to forget the huge build up towards this event after House of M. I would suggest to read the great X-Men Endangered Species as a prelude and at least a part of the Carey run, X-Men: Blinded by the Light which can be also seen as a prelude to Messiah Complex.
For Second Coming: The Cable series is considered to be really really good and adds a lot of story between the two pillar-events. The UXM issues in between were not too well received and it is not a great run but it can help to get a better understanding of what's going on. The first trades of X-Men Legacy (the newly named X-Men Vol. 2 after Messiah) were also pretty great and do follow Prof. X after the "shocking" ending of the first crossover.
I had the most issues with the the New X-Men part of Messiah because I did not know ANY of the characters PLUS they all keep talking about THE ATTACK on the school (which is shown in the also very very good Childhood Ends Vol. 1-5 which are heavily OOP and for some reason did not get the complete collection treatment yet).
I hope you enjoy the experience!