Not a nightmare, but it did take a bit of mucking around to get it right. The sub is behind the plastic trim panel at the back - I think it's nearside from memory. I don't have factory hands-free so I don't have that red plug, but I think that's right.
The other two similar sized ones are standard ISO one for power and one for front speakers - the (third) longer one is to the amp - as laid out the label on the top of the head unit - you can get these all working, you need some adapters, but you may decide not to bother. I was lucky as my replacement head unit had one of these long mini-iso connectors already - plug and play (nearly) I had to splice in my DAB box, but that's another stroy.
The next bit I am not certain on as I have gone DAB so ran a new aerial, but I think the yellow one is a Fakra aerial - I seem to recall that the aerial is a diversity system with two connections - the ordinary one we all know and love and that Fakra one too. You are going to need an adapter for the aerial I believe as IIRC the rear screen aerial module takes power from the OEM head unit. I might be wrong about the yellow plug though, it may be for the DIS.