Re: Shinzon's motives
Shinzon is a doppelganger and he's dying, he sees himself asa second rate copy of Picard and I think there's some regret about the direction of his life. Destroying Picard, earth and Federation somehow would give his life some validation.
The greatest science fiction series of all time is
Doctor Who! And I'll take you all on, one-by-one
or all in a bunch to back it up!"
--- Harlan Ellison, from his introduction
to the PINNACLE series of Doctor Who books