I've only joined OSM recently and I have finding help with OSM features on the website, thought I'd ask before messing things up.
I understand that it is not possible, unlike Wikimapia, to use GoogleMaps aerial view to trace from, some copyright issue of some kind. In which case, what can I use in the custom field to see where I'm tracing. Funny (not) tracing a house without seeing its outline. The Yahoo (why Yahoo?) option does not show and where ever I browse to 'data is not available'. I understand one can use other mapping overlays to trace from but my preference is from aerial shots as it simply shows what IS there.
In areas of interests I have roads, rivers and I would like to add features: bridges, tunnels not yet on OSM. How do I select a portion of a spline to edit a single section between vertices (OSM calls them nodes?) to change a single section of road to a bridge for example?
If a spline has too many vertices, how do I delete some to simplify the tracing or redo a whole section of road/railway?