Howdy Dav; With respect to Saddam Hussein, you asked, "But what was the hurry to dispose of him?" The main reason is because Saddam was 69-years-old and under Iraqi law it is illegal to execute anyone 70-years-old or older. Also, the Iraqi Supreme Court which turned down Saddam's final appeal ordered that the execution be carried out within 30 days. The Iraqi authorities decided that it would be better if the execution took place before an Islamic holiday that takes place during the final days of the Hajj. Is that clear enough for you?
Militants loyal to Islamic State claim suicide bombings in Nigerian capital (Reuters)
from the article: History and Hussein's hanging