question 2: what editor are you using? Potlatch? I can’t deliver an answer right now, but maybe there is a description of using potlatch and the meaning of the red circles in the OSM wiki …
The pulsating red circle means that there are two nodes in exactly the same location. This is usually an error - you should consider joining the nodes.
For closure:
“Tags” is not to be confused with OSM tags, but is used to search for traces
It seems that if you click on the tags of a GPS trace in OSM, it will search all traces that contains the same tags! (I never realised this)
The red pulsating circles explained by Richard above, indicates duplicate nodes.