-- If my thoughts are correct on the above, then Trump would need 7 more states and 1,156 delegates (currently has 81 delegates). Is that correct? --
I see it that way too.
-- What about the candidates that have dropped out. Can they assign their delegates to someone else prior to the convention, or do they have to wait until the convention? --
Good question, I don't know! My gut tells me the delegates are frozen until after the first ballot at the nominating convention, but my gut is often wrong. I am pretty sure the ability to shift delegates is determined on state-by-sate party rules. I don't think it matters, practically, because neither Cruz nor Rubio will undercut the party, so there are only a handful of delegates in potential play, even if a state party rules allowed a candidate to give his delegates to what was an opponent in the primary.
Thanks so much!