LY does'nt operate TLV-EWR via STN anymore.
The stop over at STN wasnt because of technical reasons like you can understand from COEWR post, it was to give tourists from Israel & from the US an option to make a stop and visit London on their way to Israel or the US.
The flights were operated by both 757 & 747.
Today, El Al operates 6-9 nonstop flights a week to EWR, operated mainly by a 744, but also 747/743 & MD11.
As for the details about the DL/LY codeshare and AAoperations to TLV, TWAneedsNOhelp, just try this link: