there is no real need to go up to 300dpi for prints this size, at least not if you're getting them printed commercially. What matters is the x and y pixel size, rather than the DPI.

For an A2 print you're looking at an image that is like 4670 x 3310 @ 200 dpi. Enter that into your render output settings, then your viewport will show you the frame, you may need to reposition your camera to avoid heads getting cut off etc. Bear in mind, you're talking a 44 meg image, and you're better off rendering overnight. Also, and this is most important, make sure you do a standard viewport size render first, before you set the output to huge sizes like that.

The best thing to do is experiment a bit. make say three versions of the same image - one at the settings above, one 4670 x 3310 @ 300 dpi, and one that is 2339 x  1654@ 300 dpi (half the xy size).  Then print them out. I bet you'd be hardpressed to see any difference between the 300 and the 200 version (considering the viewing distance for an A2 image is like 5 feet away).  Then try the half-sized one (you would need to fit to page or step interpolate in Photoshop to get it to fill an A2 page). Bet that will look pretty good too, and its an 11 meg file, not a 44 meg file.

You may think "omg! what a waste of paper and ink!". But you only need to do it once. Put the three on the wall and see which one you think is the best. Ask your friends over and ask them to pick the best one. Then you'll know what settings to render the rest of your artwork at ;)

Just my ramblin' 2c