That's not quite what I had in mind when I replied but ok I'll give it a go.
Multimedia for a D40.
Pioneer make head units that handle multimedia, they handle CD's, CD-R, CD-RW, DVD, DVD-R, MP3, MP4 and wav and they can have camera inputs. They all fit into a D40 dash and work a treat, and there is about 20 different models, the model best suited to you will vary on your exact requirements, but they all handle multimedia and fit in a D40.
Clarion do the same, Philips probably do the same, JVC definitely do the same and Alpine probably have something as well. All are reliable, all do the job and all fit your minimum requirements.
Ebay sellers also have cheaper options that do the same (as referred to by this thread), as to how trust worthy they are it's a risk like anything on ebay just don't get caught up thinking that because there is a Nissan badge on the picture that it's actually a Nissan multimedia unit, it's just a badge that can be changed to suit any make.
Cameras can be fitted to any unit that has a video input and a screen which is the majority of the market place and many of them you can actually buy with a camera included for an extra cost. Some have storage for things like GPS data and music storage, some require SD cards or USB inputs, but in general they all have the same features.
Look at company websites for specific models and differences (i.e. pinoeer,com.au), go to stores like JB/SCA/Autobarn etc too see some models in person but don't expect all models in stock and check out ebay for head units and select the one that most suits your needs.
Alternatively if you like dealing face to face go down to your local auto shop and see what they have in stock, get the model numbers, go home enter those model numbers into Google and look at the models and their specs on line and return to the shop with your money.