1) You are there on a holiday. Telling them you are self employed and going to work in an office you are renting there is only asking for trouble. It confuses the hell out of them. You think where you do the work from doesn't matter, they think you need a visa. You lose.
2) If you are going for a conference, print the badge off before your flight and have it with you.
3) Email or upload all your files to dropbox/some server in a TrueCrypt container, and wipe all devices you will be crossing with, including your phone. What do you need them searching through your stuff for? Who knows what they will do with it. It's just asking for it.
Yeah, right. Social Engineering is much easier than gaining access through some 0-day attack you have devised yourself, or even finding some working skiddie method (when dealing with a specific target). For one thing, you don't actually need any actual skill, you just need to be a good liar and have a good story. That's not skills, it's just a sociopathic trait some people are born with.
You're so glad, really? This guy was apparently Christian, so I hope that makes you feel better about the religious aspect of it. Extremists and fundamentalists are all the same, regardless of what they're worshiping.
Also, given that Islamic extremists would be the most obvious conclusion, how is it unreasonable to draw such assumptions, especially when a supposed Islamic group claimed responsibility?
They're going after these people to make an example of them, not because they did anything actually harmful.