You are expected to hold the right mouse-button pressed down while scrolling the map in JOSM, not right-click.

As someone who has already spent thousands of hours in JOSM and so probably would top a few lists, I would be very wary of gamifying anything OSM. Because how would you really measure the “value” of a contributor going out of his way to provide quality (takes his time to draw accurately rounded curves or spot all sorts of mistakes, etc.) relative to someone who (apparently) just cares about throwing lots of nodes and ways onto the map (I’ve noticed a few examples of that). At this point I just can’t imagine a way to effectively differentiate between the two without throwing insane amounts of manpower at it, in which case it sort of seems moot to me.

Throwing more nodes and ways at the map doesn’t necessarily make it better.

I too would very much appreciate an option to filter out nearby users who never made an edit or those that wasn’t active for a given amount of time.

I have a Garmin 550t https://buy.garmin.com/shop/shop.do?cID=145&pID=26876&ra=true
which is just plain great for mapping :-)

Pretty off topic and not even true...

Try going to http://josm.openstreetmap.de/. It looks like JOSM is partly translated to Arabic allready.

In Ribe, Denmark, where I live, there's a river running through a landuse=residential. It's rendered fine in both Mapnik and Osmarender. The river was tagged layer=-1 when I first found OSM 10 days ago.

I tag rivers and streams layer=-1 so I won't have to tag the bridges going over them layer=1