As far as the negotiating with terrorists issue, I don't think you have to worry about that, at least not more than you should have before (maybe this is a case of ignorance was bliss, haha). First, the Taliban isn't technically a terrorist organization, it is a religious fundamentalist political group (and the ruling government in Afghanistan at the time of invasion), the US has been trying to get them more and more involved in the new Afghan government the past few years (yes, they did let Al Qieda (sp?) train/exist in their land but so do many other countries). So, if we did want this kid back, negotiating with them to do it isn't really breaking with any tradition we have had in the past.
Now, as far as our history of negotiating/working with "terrorists" we actually have a pretty long one as a country. The main ones that come to mind as particularly relevant in our current period would be the supplying of weapons/training to Al Qieda to help them fight the Soviet Union and Iran Contra. Democrats said the same things Republicans are saying now as far as how the terrorist groups would respond by seeing kidnapping Americans as a good strategy but it obviously never happened.
As far as the kid himself and what he did or didn't do to get kidnapped and the cost of his actions that's not something I know enough about to have an opinion on.
What I would take from this is a pragmatic view. Yes, if you negotiate with terrorists and people know you will than you will become the victim more often. Fortunately Obama typically responds with Drone's and not negotiations so I don't think we have to worry about people thinking the US is not willing to kill their asses. However, if you do not negotiate at all then you resign yourself to either never ending conflicts, like we have now in a way in Afghanistan or you must completely defeat your opponent, something that we have not been able to do the past 13 years given the moral view of war in our society (we can't just carpet bomb Afghanistan and kill every living thing, lol). Since neither of these options is both good and possible it leaves us with negotiating.