Citation Captain reported on initial approach being high and fast resulting in flying an unstabilized approach with flight towards terrain. The Captain executed a go-around and landed safely on the second approach.

Narrative

I was paired with a copilot who was very competent; energetic; quick witted; and knowledgeable about the Garmin avionics system. It soon became clear he had more knowledge than me; and I spent some of our time asking about the system and trying to improve my own level of competence.The moment came when we were flying into ZZZ. We were kept high due to the surrounding mountains; and our speed was still 200 knots as we approached the inbound course. I was already getting task saturated at that point; and only at flaps 2. At that point; the controller asked us if we wanted to turn outbound to slow down. The copilot responded; 'No'; so the controller turned us on course. Now we were high; fast; and not configured; just a mile or so outside the FAF. At this point I was now basically a passenger; and the copilot began directing my actions; telling me we needed to descend and configure. I blindly followed his direction; and my scan began to deteriorate as I struggled to get the aircraft into a landing configuration. We were so high the GS diamond was at the bottom of the indicator. I heard a 'Sink Rate' warning as I saw 2500 FPM in my attempt to catch the GP (guidance panel). I saw an amber 'terrain' warning but heard no callout. None of it made an impression as I struggled to get on the GP. Finally; the copilot said; 'go around' and I initiated a sloppy go-around procedure. I noted as I was climbing out that I was pretty far off course to the left. Looking at FlightAware later I believe we were near 8;000 feet left of the localizer. We climbed up to a safe altitude and recovered the aircraft. We went back and flew the approach again; this time with no complications.Suggestions - There are several issues here. First; while my knowledge of the system is sufficient; I know I have much to learn. Because of this; I tended to defer to the Copilot due to his higher level of knowledge. Unfortunately; he knew this; and assumed the role of teacher even when it wasn't necessary. When things started to get complex; he assumed the role of defector PIC; telling the controller we could make the approach from the tight position we were in; without consulting me.I knew an older pilot here who was well respected. He flew competently because he slowed everything down; which is what I should have done. I should have interjected and countermanded his response to the controller and asked for a turn outbound to slow; descend; and configure.I can only recommend the following; especially for a pilot new to an aircraft; or an older pilot who may not be as mentally quick as he or she once was.1. We brief PIC/SIC responsibilities. We should strive to remember our duties and responsibilities. This will help avoid the Transfer of responsibilities" which occurred here. The change was subtle but rapid when the time came. The copilot decided he could have made it from there; so he decided he could control things through me. This was a near-fatal mistake of over confidence.2. Slow down! Had we done that none of this would have happened. Especially older or less experienced pilots."