It is possible to name a "highway" in multiple languages using name:en, name:jp, etc.

Is it possible to tag the address of an object in multiple languages (addr:street)?

I have a seperate highway with two plus two lanes (total four lanes). I want to map a u-turn which is a third lane with a stoplight (at the stoplight there are five lanes in total).

Does anyone have any suggestions? A link to a wiki which describes this or a link to an actual map location doing something similar would be very helpful.

I loaded my GPS traces in Potlatch 2 and was unable to see them.

I realized that they are hidden between all nodes and ways which are being drawn on top of the traces. It like three layers: background, traces, and rendered map data.

I would have expected that traces are shown on top of the rendered map data rather than the reverse.

What is the best was to show GPS traces in relation to the map data?

I have been comparing maps and satellite images from both Google, Yahoo, and Bing and for the same location I found different lat/lon values. I saw a reference to the Bing accuracy in wiki. Which of the six combination is most accurate or does it depend on the location?

I also found a reference to the accuracy of GPS traces. I understood that it very much depends on your receiver, the day (if not taken on the day they can be quite off). What is the best way to get accurate traces? Is there a way to create a "average" trace based on a number of trace? What should I rely on more, maps / images or GPS traces?