This Page @ co.com Addresses Most Of Your Questions
EUA's do
not happen on sectors marketed as BusinessFirst
While EUA's can happen on sectors not marketed as BusinessFirst (such as you SFO-EWR flight), the free upgrade is
very hard to score. However, you will be eligible for the upgrade on this sector (SFO-EWR) but you will not be eligible for the EWR-Europe sector.
Also note, as a SkyTeam Elite Plus (which you are as CO Plat = SkyTeam Elite +) you can access any SkyTeam lounge if you're traveling on an international flight operated by a SkyTeam partner.