Setting up AlwaysONAG in SQL server 2016 on windows 2016
This is generally a consulting engagement since there are lots of minutiae. But to answer your techincal questions:


The AG handles the data synchronization process. There is no storage-based replication needed or involved with AGs whether it is local or multi-site.
You can use the NJ site as a FSW, but arguably the best option for multi-subnet in WS2016+ tends to be cloud witness.Figuring out the right witness for quorum needs a bit more informaiton about your infrastructure, which is again, generally a much deeper consulting engagement.


Also, it's not AOAG. Just AG. Always On (which has a space) is just a marketing umbrella term which covers both AGs and FCIs. The ON is not captialized.