Frank, welcome to the forums! Like you, I didn't know how to drive stick when I got my MS3....in fact, I tried to learn online before I went to the dealer so I could test drive the car without embarrassing myself
Don't get too worried about it. Practice sitting in a parking lot with the car started, put it in first, and let out the clutch SLOWLY SLOWLY SLOWLY until you hit the engagement point where you feel the car start to move, and hold it there....let the car roll for a while without giving it gas and then push the clutch all the way back in and brake to a stop. Do that over and over to get the feel for where the clutch engages in 1st. It'll take a few days to learn that without stalling the car...so give yourself plenty of time.
After you master the clutch engagement point, right after it starts to move the car, give the car some gas (just a little, not to the floor), as you SLOWLY let the clutch out all the way.
When I learned on my Speed3, I'd never driven stick before (I'm 29...always had auto cars), and all kinds of people told me "OMG YOURE GOING TO HURT IT".....I stalled it about 6 or so times starting in first over a day and a half, and then I got it down pretty good. Don't worry about hurting the car as long as you take it slow and you're careful. Don't rev to 5500 and let out the clutch...that will hurt it. But if you're being sensible, at slow speeds to learn, you won't really do any damage.
The most important thing is to practice in a place with no traffic. Nothing is worse than sitting at a red light with 20 people behind you beeping at you after you stall your car...so learn in a private parking lot where there's no pressure, so it's second nature to you when you're on the road.
To answer your 3 questions.....
1. When you start the car up, and have the clutch pressed in, with gear in first, as you let it out, the rpm's WILL drop as the clutch engages and tries to move the car....that is normal, no worries. The problem comes in if you keep letting the clutch out fast, without giving it any gas to compensate for the drop in rpm's as it engages. (That's what stalls the car)
2. Studdering? You mean right before the car stalls? That means the car doesnt have enough power (not giving it enough gas) to compensate for the amount you've let out the clutch...(You'll also see some studdering when you're driving in first gear and you let off the gas hard, the car will kind of jerk you back and forth a little bit)...
3. By throttle response do you mean where the clutch engages? I had a heck of a time figuring out that the slightest movements of my left foot caused the clutch to either be engaged fully, or not engaged. Throttle response for me is fine....especially in like 3rd gear at around 3k rpms, any little tap of the gas pedal pretty much will push you back in your seat.
Have fun learning! Be safe!