Both of these issues are actually dealt with on this site.
Search this site for drilling and you'll see some references regarding the slant-drilling. The sources aren't the greatest, so if you find any more information regarding this then post it here.
Regarding the US telling him it was okay, look under the First Gulf War
section. The US ambassador might have not exactly said 'go ahead and invade', however it appears he in any case gave him the 'green light' in not saying that it was not ok to invade.