I fitted one of these "CK-O DAB2011 V2 with improved display" from here
http://www.dabonwheels.co.uk/CK-O_DAB2011.html
and this roof aerial "Kinetic DRA-6006 DAB - DAB+ / FM-AM car aerial"
Great performance for £145, easy to fit and reliable.
DAB needs an external aerial unless you stay local and you live in a strong signal area.
I did not have an RNSE but it just uses 2 RCAs for audio and 1 for video so if you have the inputs available RNSE will work fine (not sure if the RNSE resolution is up to it though)