2) Strategic advantage: DAs are usually the strongest arguments. Introducing DAs in the 2NC makes it so that the first response is given in the 1AR, as opposed to the 2AC. It is much easier for aff to respond to a DA in the 2AC than in the 1AR.
I respectfully disagree.
Coming from someone who has almost always been the 1A, it is much easier to respond to DAs in the 1AR than it is to respond to Significance/Solvency arguments. First-level disadvantage argumentation can normally be quickly de-linked by a well-prepared affirmative, or simply lumped and collectively outweighed. On-case refutation, on the other hand, requires in-depth analysis/details to respond adequately (because the burden is on the affirmative to prove their case and answer logical objections to it, whereas disadvantages are negative arguments, which means that negative has a greater burden in the minds of the judge to support their position). Meanwhile, until those arguments are addressed, no disadvantage can be outweighed because the case itself is unproven. While DAs have a stronger impact in most rounds, it is the on-case argumentation that typically requires the most complicated and time-consuming response.
If your DAs are truly the strongest arguments in round, my advice would be to present them in the 1NC so that the judge immediately has a reason to vote against the case (as opposed to on-case arguments, which normally aren't a reason to prefer negative). If you are well-prepared, those disadvantages can be easily extended past the 2AC's reponses in the 1NR, leaving the 1AR with complex, second-level response argumentation instead of the usual clump-delink-outweigh response structure. Meanwhile, the on-case refutation comes in the 2NC, leaving the 1AR with the difficult task of re-explaining and giving additional detail to the 1AC affirmative argumentation.
That said, different strategies work best for different teams and different cases. Split the negative can work well for teams who prefer it. Personally, I prefer shell-and-extend when possible, or Emory switch (split the negative, but with the DAs and Solvency in the 1NC as opposed to the 2NC).