The Udina/Kai Leng situation in Mass Effect 3? Can you get the best outcome without playing ME1 and 2?

I had just finished "Priority: The Citadel II" mission, but this was the first time I did it with imported saves from both ME1 and ME2. I have some questions about that mission for those of you who started Mass Effect 3 fresh without ever playing ME1 and 2.

My first time playing Citadel II last year, I thought ME3 simply picked up where ME2 left off, so playing the other 2 weren't necessary. ME1 didn't even exist on PS3 then.

I didn't know unfinished Citadel side missions expire after Priority Tuchanka, so I missed some of them. Kai Leng killed that counselor, and I picked the "R1" button which killed Ashley. I was so mad, I went out and got ME2, and didn't even finish that 1st playthrough. I now realize that if I didn't press R1, one of my squad mates would've shot her anyway.

When I played ME2, with a nearly perfect ending, I had Thane show up in ME3 to stop Kai Leng's assassination attempt, I got the blue dialect option to slowly convince Ashley to take our side. I believe she was the one who shot Udina. Later, I had to do some convincing to get her to turn down Anderson's offer, and rejoin the ship.

Now, I just finished Citadel II yesterday, but I imported a nearly perfect ME1 playthrough (I only messed up Conrad Verner's missions), and a perfect ME2 playthrough (all loyal, no deaths, not even any of the abducted crew), with every downloaded content for all 3 games. I also completed all side missions before doing Priority Tuchanka.

This time around, after Thane saved the counselor, I got the "L1" option when I ran into Ashley. I didn't even get into any type of argument with her, and I got the "R1" option and shot Udina myself.

When I ran into Ashley outside the ship, I didn't even have to convince her to turn down Anderson's offer. Before I could really say anything, Ashley said that she would rather rejoin the Normandy, and I got her back without trying. She wasn't my love interest, Liara is.

QUESTION 1: Did it matter that I took Garrus and Liara with me, Ashley's squad mates from Mass Effect 1? I took those two specifically for that reason. I remember at the end of the Mass Effect 2 Horizon mission, Ashley goes off on both you AND Garrus if he is present. If he's not there, then you face Ashley's wrath alone.

QUESTION 2: What if I had taken EDI, who now occupies the robot body that sent Ashley to the hospital for over a month? Does Ashley say something about that?

QUESTION 3: If you start off with Mass Effect 3, Is there a way to get the same result I just did?