Excluding a strange circumstance, you wouldn't find it a bit annoying?
It depends. If the neg knows what they're doing and knows how to defend it I would find it awesome.
Is the Affirmative allowed to change their position of advocacy from the 1AC to the 2AC? As in, are they allowed to change their plan in the 2AC? Most people would say no.
Most people in the NCFCA would say no. In college policy debate, it would be about a 50/50 split of yes and no. I would personally say yes, the aff can. It's called a constructive for a reason. Strategically, it's usually a bad idea, but from a theory standpoint I'm fine with it.
The Negative should be held to the same standard. Their position of advocacy should not shift from the current system to a counter plan in the 2NC.
There's a theory called multiple worlds that I, and most college debaters/coaches, adhere to that says this isn't correct. Multiple worlds says the neg can have multiple advocacies, even conflicting advocacies as long as two conditions are met:
1) They all negate the res
2) By the rebuttals the neg has one advocacy
The theory is that, because the neg's only job is to negate the res, not actually propose a plan, as long as they negate the res they can do whatever they want. Therefore, any way they choose to do that is perfectly fine. Of course, all those advocacies should probably be laid out in the 1NC for strategic reasons. (running a CP you're just going to kick in the 2NC really sucks your speech time, plus running everything in the 1NC lets you see all of the aff's responses and choose the more winnable position, versus picking blind in the 1NR) However, since the neg can have more than advocacy, they can "change" (read: add to) their advocacy any time during the constructives.
On a strategy/argumentation level, a CP in the 2NC is just a bad idea for the negative team. That least less than half the round to debate/clarify the CP. Also, a CP in the 2NC almost certainly wastes lots of debate from the 1NC/2AC.
Sometimes the best way to come back from a horrible 1NC and/or great 2AC it to just make it go away. But, in the vast majority of rounds, I agree with you.