My agent told me that this editor in chief is a friend of his and usually reacts quickly but in this case he thought he would pawn it off to the editor that showed interest before taking it on himself. Is there a 'slush pile' for agented / solicited materials as well?
"Pawn" it off doesn't sound too god to me. Do you mean to say that the editor-in-chief will give your work to the appropriate editor (must work with the genre of your book) who displays the most desire and demand to work on the book?
As far as I know there's only one slush pile for all.
My last question is about the acquisitions meeting:
After this meeting do they have an answer or do they sometimes go unresolved?
Many go unresolved at any given meeting and are put on the agenda for the future -- not enough time to get to it, discussed but research has to be done, further thought needed, etc. Remember, these meeting usually take place once a month - at best twice -a month and are attended by a slew of departments including editorial, sales, publicity, production, creative, and subsidiary rights. And basically all must agree that it's wise to purchase, produce, and market the book. So, objections (or questions) can come from any of these sources. They are trying to make a wise business decision.