I'm certainly not an expert, but it's something that I've read about over the years.
My thoughts? He knew what he was doing and he had a plan. That having been said, there's no small amount of evidence that he didn't make it. Besides the fact that it was a risky jump (admittedly he had no other choice and he took some steps to make it safer), a few thousand dollars washed up on the Colombia, his choice of parachutes was questionable (he picked a dummy as his reserve, so he basically jumped without a reserve), and the big one: besides the money in the river, none of it ever turned up. That having been said, had he waited a decent amount of time before spending it, spent it carefully, and made sure to launder it to some extent, no one would have noticed the money when it went back into circulation.
Interestingly enough, Christiansen bought his house...what, a year after this happened? Long enough for things to settle down a bit. I would have waited longer myself but I don't know his situation. A guy doesn't hijack a plane and make a night jump at 10,000 feet over Washington's back country if he has other options. Breaking down a few thousand dollars by the twenty would have been tedious, but a year would be long enough to do it. After a few more years, no one would be looking for it any more and he could be a bit more aggressive with how he spent it. But hell, given the amount of planning that went in to getting the money in the first place, whoever Cooper was, I have no doubt that he had plans for how he'd dispose of it if he was successful. You don't plan a heist like that and then haul it all to the bank or casino the next day, after all.
Another hint that intrigues me is that he made his move on the night before Thanksgiving, giving him a solid four day weekend before Monday morning. If he'd had a day job, he could conceivably hijack the plane on Wednesday afternoon, be on the ground by Wednesday evening, and (hopefully) be back at work on Monday or Tuesday. I don't think that the timing was accidental. If we accept that this was part of the plan, Cooper had a Monday-Friday job and expected to return to it. This is significant on several levels.
Was he a local? Probably, but it's not beyond the realm of possibility that he simply spent a few minutes with a map (or even had a map on his person) to get the lay of the land, then let that knowledge slip ("That must be Tacoma down there..." Well, since we just took off from Sea-Tac a few minutes ago and there's now a large city below us, yeah, that pretty much has to be Tacoma. You don't need to be a local to know that) in order to appear to be a local. He also knew things about the plane that the average person (or even flight crew member) would not have...also significant, if you ask me.
