In short, I don't care. I'm not a strict constitutionalist. I don't place value in the constitution in and of itself. I value the constitution because I think it is a very useful and well-written document for establishing reasonable powers and limits on the government. But the constitution is not a flawless, holy document. Times change. There are issues addressed in the constitution that are completely obsolete and meaningless today. And we face other issues today that are not addressed in the constitution, issues that the founding fathers could not have possibly anticipated. Regardless of whether you agree with it, the powers granted to Congress in section 8 have been interpreted quite broadly - in part, to give our government fluidity and the ability to adapt with the times. So, I'm not interested in debating whether the AUMF is constitutional or not because it doesn't matter to me. What matters to me is whether or not it's a good thing.
Besides, whether or not the AUMF is constitutional or not is irrelevant until a federal court rules on its consitutionality. Our government is set up in such a way that all legislation is assumed constitutional until a court says otherwise. So, despite what you say, the AUMF and the Patriot Act are currently legal and are going to be implemented and observed as if they were legal until a ruling comes down overturning them.
Purely from a strategic perspective I am highly supportive of the drone strikes. Pivoting away from heavy-handed, full-scale invasions and relying more on special forces operations and focused surgical strikes on terrorist leadership is absolutely necessary and has been quite effective so far. The Al-Qaeda leadership in AfPak has been decimated, and is the major reason Al Qaeda has been forced to retreat west into Yemen and the Maghreb. As with any military action, blowback is a legitimate concern. The drone strikes are extremely unpopular amongst Pakistanis, for example. But in Yemen we are not witnessing the same popular backlash, partly because the strikes have become more effective with fewer civilian casualties as our grasp of the technology improves.
Despite what everybody's been saying in this thread, the Obama adminstration has in fact made an effort to lend transparency to his drone strike strategy. Obama has declassified the drone program in Yemen (though not in Pakistan) and has made public the details of the
review process that is followed to determine if an Al Qaeda suspect is dangerous enough to warrant a strike, which is appears quite rigorous.