Neil Gorsuch -> Fair enough, tho like others said, he's pretty much "replace Scalia with another Scalia," tho tbh the few things I've heard about the guy make me a little worried.
Canceling Nasa's Asteroid redirect project (it sounds cool, but if you think about it, it's really stupid) -> I'm not entirely sure why this is stupid? Having the capability to redirect an asteroid, considering what they've done in the past, sounds entirely like a Good Thing. And having resources in space we can mine instead of expensively shipping up metal or manufactored goods is a fair plan, depending on how expensive the redirect+mine+refine+manufactor turns out to cost in the long run.
Decreasing the dept by 100 billion -> Well others have gone over this, i.e. that it hasn't actually happened yet, that it's based on a budget that double-counts a lot of shit, that even if it were true, it's a drop in the bucket, and that the cuts that he wants are less "trim the budget" and more "hah, fuck you libs," like cutting really small things that cost literally less than pennies per person, like arts programs and youth programs and after-school programs.
The misslie strike on Syria -> Fair enough. I'm not a huge fan of it, but that's as much personal opinion as anything; I won't argue on it. Others have said things like "it might have been an Obama plan" but I don't know enough to say anything about it.
Approving Keystone pipeline -> ... Why? What's so good about the pipeline? Oil is kinda shitty, and it's dirt cheap now so not much profit to be made on it, and it's on the way out. Not really sure why building an expensive pipeline that fucks with a lot of people and probably won't pay for itself before it goes obsolete is a Good Thing.
E: Comey: I can see that. I think the main problem with that is the optics of firing the guy in charge of investigating something you're a key part of. If he had instead gone to Comey and said "Find me a good replacement for you," (or asked someone else part of the FBI, so it doesn't just seem like Comey gets replaced with a Comey puppet (even if that probably wouldn't have been the actuality)) and been more careful about it, making sure it looked like more of a "I'm getting rid of the person who everybody dislikes and putting in someone independent with a clean slate," instead of firing the guy who's troublesome for him through a letter in a courier and not actually having a replacement for the investigation, I think it would have gone over a lot better.