1: atlantis never got hit by the replicator satalite weapon as it fled Lantea as the shields had managed to get up in time so she was never replaced.
2: teyla and ronan are a couple and shepard and DR.weir are married (They married after the end of SGA)

3: the RP will start just after the backstory ends roughly.
4: the 2 ships come from an alternante Universe/time into the main cannon SG universe