1. There isn't actually a JRiver iPad app. There are third-party remote-control apps, such as JRemote and MyRiver - do you mean one of those? There is, however, an official Android app called Gizmo and there is a browser-based version called WebGizmo.
2. If you are running Twonky on a NAS then actually any UPNP/DLNA controller app will work with it. Is there any reason you want to use JRiver? JRiver is able to connect to a DLNA library server such as Twonky but I don't really think there is any advantage of doing this, unless you are playing media on a PC in which case you could take advantage of JRiver's audio and video rendering technology.
3. You could alternativelyan also use your NAS as a file server rather than a media server (i.e. switch off Twonky) and allow JRiver to import its library from there. It's just like using an external hard disk as storage which, in turn, is effectively just like using a local hard disk to JRiver. If you do this then you can take advantage of JRiver's fantastic tagging, cataloguing and view-creation facilities.
