1. No. You should disconnect them. Same with you, I believe it is erroneously connected , since it looks like it is supposed to follow the Haycock Road overpass.
2. help.openstreetmap.org is more for straightforward or topical questions. OSM Forum, Reddit, Discord, or whatever your local community , if you need to have detailed/exploratory discussion.
3. First of all you should note that some imagery is outdated. I suppose this section has been recently widened and remarked? Now on your question, there's the matter of OSM history, and backward compatibility. What are you are seeing now and thinking about doing yourself is the "old" way. Lane-based features are newer newer, and you need to check know if Tesla or the source they are using actually support such navigation mechanism. What are you are seeing now and thinking about doing yourself is the "old" way. Ideally, this is not correct, as mechanism to have any effect. Since there's no physical separation between the white solid line delineated lanes. lanes, the "old way" is ideally incorrect. There should simply be `turn:lanes=through|through|slight_right|slight_right` + `destination:lanes=none|none|Dulles Airport;Baltimore|Dulles Airport;Baltimore` + `destination:ref=none|none|VA 267|VA267` + `destination:to:ref=none|none|I 495|I 495` on the approach, approach to guide drivers, then `change:lanes=yes|not_left|not_right|yes` on the white solid line marked section. You should consult with other editors in this area on this issue.
4. Unfortunately the iD editor has implemented very stringent editing rules, because the node here connects ways in relations. It can only be disconnected in JOSM. You can ask someone in the area to review and help you.
