Hi, it looks like you did not account for the fact that building walls are visible in the imagery you're using to map footprints. 

When mapping with imagery captured at an angle, please position features where they are at ground level. You can map the outline of the roof and then reposition the building to the base of the walls. I recommend you watch this [video about mapping dense urban areas](https://youtu.be/JAPiGntG6fs) and read this [written guide](https://wiki.openstreetmap.org/wiki/Roof_modelling#Typical_errors_in_the_interpretation_of_roof_geometry_from_aerial_images).

You created a node shared by a building and a highway; this should only occur in special situations. Hold alt to prevent this. 

Please do not connect the corners of buildings to other buildings or features such as highways or residential areas. In the iD Editor, hold down the `Alt` key to prevent your cursor from snapping to existing data and accidentally creating shared(grey) nodes. This [video about connected nodes](https://youtu.be/ltn1VOiq5_0) has more information and a guide.

I hope this helps.