How tall and wide could the Eleagnus get?

The Eleagnus on its own can grow to 10-15 feet. If it has support from a fence or tree it can grow up to 30ft tall.
It makes for a great privacy hedge.

Will these work in zone 7 in "mostly shaded" area?

Eleagnus will grow in zone 7, however Eleagnus needs mostly sunny to thrive.