I recently - reversed into a star picket lol - left a nice big fat dint in my rear

www.stephan.mercness.net.au/dint.jpg

1) how can I get the dint out - would I have to do it myself, or get a pro
2) the paint has come off more than that now - how do I stop more coming off
3) will this be the much needed incentive for me to get a respray (about a million stone chips all over the car)

If there are no holes/tears, then it should be able to be popped out. You can try this with a hair dryer, but would probably be easier to get a pro panel shop to do it. You'll find the bumper will need respraying, so you're up for a couple of hundred there. Get a price on a full respray while you're there, see if it's worth it.

If that was an insurance job the panel shop would likely get a new bumper bar. It could be popped out, but it would take a bit of repairing, especially if the plastic has been stretched, and it looks like it has been.
Depending on where you go, paint will cost from $160 (dodge)-$350 (top quality). Then you would pay repairs on top of that.
To stop it going further you could either rub back all the edges with sand paper until they are feathered out or you could use an air blower (on a compressor) and blow it back until it stops flaking. It will eventually get to a point where the paint is sticking hard enough, but a fair bit of paint will have to come off first. What ever you do, it won't look good unless resprayed.
For a full respray. The same colour, all over, from a regular crash shop would be fairly expensive. You won't get a quality job for less than $5000 from a crash shop. It is possible to get a private job done on it, if you know someone willing to do it, and even then you are probably looking at $2500+, depending on the paint they use (Glasurit, Spies Hecker, Sikkens are GOOD - PPG, Debeers are OK and Protec, Chemspec and Cobra is CRAP).
Hope this helped, and this is only from my limited experience as a 3rd year Spray Painting apprentice.

Cheers,
Cam.