Can't help on the Asus NAS control app, I just use Plex for streaming from my networked spare drive, which is easily accessed by my laptop if I want to swap or update files.
Avaition Weather app such as Metar Weather Map?
http://www.windowsphone.com/en-gb/store/app/metar-weather-map/f901b638-2d6d-49f0-8daa-32cacbe41a8c
As for banking, which bank? Natwest = best, others are mostly web-wrapped apps, like mine, Lloyds works, but nothing special like my missus Natwest, which is fast.
Iplayer, checked. (No download yet though)
TV Catchup, checked.
Reddit - Try Baconit, brilliant Reddit interface.
Instagram, checked, but it's in Beta. I use that but I also use 6tag. Most of 6-something apps by Rudy are better than official (if any)