Yeah, turn on iCloud Sync on the old phone, synch everything you want to keep, turn on iCloud Synch on the new iPhone, wait until everything is there, and finally shut off Find my iPhone and all other iCloud services on the old iPhone. You should have everything.
Or, backup your old iPhone and setup your new iPhone from the backup. That can be done to iCloud or a local computer running iTunes.
I have an ipad air 2. Rarely use it these days but I wanted to render out some videos to watch while on the treadmill. I have them in wmv format and looked online to see if that would be compatible. The Google searches claimed wmv would not play on my ipad air 2. But I uploaded to my Dropbox account and they play fine. However only from Dropbox and not after downloading to the ipad. I'm currently rendering in mov file format so I don't need the internet. Just wonder if any of you know if there is a way to get the ipad to play wmv files.
I don't have experience at home with the Synology NAS but they have a + line of NAS that will transcode on the fly and iOS Apps for viewing. But your solution of saving in an open standard format is probably best.
At work I end up renaming MP4 files to .WMV so our IIS server understands the extension. It's easier for me to do that then adding the IIS configuration change to understand the MP4 extension...
Most NAS devices come with some sort of media server now and if they don't have one, there's often one available (Twonky or Plex). The issue is that the cheaper devices don't have the horsepower to decode some of the more complex schemes and that's where a conventional computer with a modern display adapter will serve one better.
IIS is another bit of irrefutable evidence that the Internet and Microsoft have never been particularly well acquainted.