Reports: Bolton In Talks About Possible Impeachment Inquiry Testimony

John Bolton has been in discussions with House lawmakers about potentially testifying in the impeachment inquiry. NBC News reports that negotiations are ongoing with Bolton's legal team to schedule a closed-door deposition. Bolton has been mentioned in other testimonies regarding Ukraine and the White House. Fiona Hill, a former top Russia adviser, stated that Bolton was disturbed by efforts to involve Ukraine in investigating Trump's political rivals, likening it to a 'drug deal.' Hill also mentioned Bolton's description of Rudy Giuliani as a 'hand grenade.' Bill Taylor, the top US diplomat to Ukraine, testified that Bolton opposed the July phone call between Trump and Ukraine's president. Bolton left the Trump administration in early September after disagreements with Trump, with conflicting accounts on whether he resigned or was fired.

What was Bill Taylor's statement regarding Bolton's opposition?

What were the circumstances surrounding Bolton's departure from the Trump administration?