Debugging on Visual Studio is not possible out of the box, but there's a commercial add-on for it: http://unityvs.com/ I don't know how well it works since I don't have VS Pro and it doesn't work with Express (also I probably don't want to pay $100 for something like that at this point).
How recently have you tried Unity? They recently upgraded the MonoDevelop version included with it in 4.3 so it's better than it was... though still hardly perfect. I have some stability issues, but nothing as bad as what you described.
I know about UnityVS, but I'm making games just for fun, not gonna pay 100$ :/
I've tried multiple versions of Unity, form 2.x to latest, 4.3, I had issues with almost every one of them. As I remember, previous code editor was much more stable.