I think my lack of communication printer -> router -> computer is down to the router rather than the printer. It's a Draytek, and the manual specifically says it's one way only for printing.
My Pixma (IP4000) is a couple of years old, but excellent. It does that double-sided thing, and does it very well. In fact, it has one big advantage over the later models: there are no chips in the ink tanks, so they are a lot cheaper - and I can use "alternative" ones, still excellent quality but a fraction of the Canon price. A friend bought a later Pixma on my recommendation, and is very cross about the cost of inkpots. Apparently you can't refill them yourself for very long either - the printer cottons on and refuses to accept them.
Deano777 - is it sorted now, or do you need more ideas?