In the relevant thread on his Facebook page, James Gunn comments on the Guardians of the Galaxy movie connections in regards to the rest of the Marvel Studios films - or maybe we should say the lack of connections. Gunn also sheds some light on the use of Thanos and the Infinity Stone.
I wish the MCU was that planned out (or do I?) But it simply isn't. The ONLY thing in GotG that was connected to the rest of the Marvel Universe is the existence of Thanos and the existence of an infinity stone. Everything else - how Thanos was connected, who he was connected to, what were the properties of the infinity stone, etc, etc, were all basically made up by me. It's much much looser than people think it is. And it certainly wasn't planned out when they did Iron Man. They just thought about making a good Iron Man movie - which is exactly my point.
James Gunn also previously mentioned the organic nature of Guardians of the Galaxy when he confirmed future Marvel Cosmic movies. Gunn said he doesn't feel "beholden" to what's going on in the rest of the Marvel U., and Gunn specifically said, "Guardians 2 is not a movie that’s made to move toward Infinity War."
Guardians of the Galaxy 2 has a May 5, 2017 release.