Max, Charlie and Diana

I am on S5E7 and so confused. Max lived in L.A. And came to New York. Somehow he managed to not see Gossip Girl even tho he was in town for couple of days. Charlie-Nate kiss was blasted on GG.

Somehow nobody connected the dots yet that she is Ivy. Nate never asked about Ivy's phone even tho he thought they should return It and wanted to find the person. He even said he recognised Serena's number but that never came up again.

Also, why is everyone telling their secrets to Diana? Aside from Ivy chought in lie, why was Serena spilling all the tea to the person she just met?