IF FE2 isnt Cannon (wich it is btw)..BUT... if they dont class any element of FE2 or FFE... then Frontier should completely KILL Colonia's bubbleoff and especially Jaques Station, and the whole concept of the Federation and the Empire (wich were first introduced into FE2), but your right they ignore the sequels
Nope, i dont think any of the older Elite games are cannon for the ED universe, and i think i've seen it written by a CM - they've rewrote (some if not most of) the history for ED.
Basically, for ED lore you need to check only the articles and the stories that are related to ED - so published novels related to ED and Galnet news and articles.
Travel is different in ED, timeline has differences, there are no (space) aliens - like in alien civilizations engaged in trading with humans, except the some of the atrocities against native lifeforms during the colonization process. There are no friendly Thargoids.
Basically for ED they retconned most of the timeline, and i repeat, i remember them saying that events in previous versions of Elite are not cannon in ED.