They say they are working on it, but they have released almost no info. All we know is that it runs on Catherine's engine which implies a PS3/360 release.
No they didn't. They said it will be using a new engine that is different from Catherine's.
Right now P5 isn't the top priority no matter how much any Persona fanboy (not the regular fans) whine about it. It's in development but Atlus are waiting until it's closer to be done to reveal information. That always been Atlus' style. SMT4 is coming out next month. There is no way Atlus is going have P5 steal its thunder. Then there is Break Record. EO1 remake, and SMT x FE coming out later. P5 might get announce later this year. Either way you had to be naive to think they would show P5 at a western event first. The Japanese get first dibs.