1: A lot of failures could be attributed to someone forgetting their training due to stress... but he didn't seem under that much stress and evidently forgot all of his training. That's pretty suspect. You shouldn't be able to get a certificate without showing that slow to best glide, start looking for a landing site, and start the engine out checklist is a set of steps that you can conduct quickly from memory. It should be trained into pilots to do this kind of thing out loud (e.g. pointing and narrating) because the instructor and examiner want to see it that way and it just helps you keep on track and concentrating. That makes it odd that, if any of this happened, he omitted it from the video... from a vanity perspective it's an opportunity to Look Like A Real Pilot by working your list in an authoritative voice (I'm pretty sure every pilot gets a kick out of saying Landing Assured, otherwise they haven't found out how fun it is yet).

Of course we can't totally tell from the video but it really doesn't seem like he took any of these actions prior to bailing out, certainly we don't see him with a checklist. Bailing out isn't even really something that's discussed as an option in an engine-out scenario, it would have to be such an unusual situation for it to be the best choice and it will tend to endanger anyone/anything on the ground (and of course it's a goal of aviation not to do that). One thing that is explicitly trained for any kind of precautionary (e.g. "this might go poorly") landing is opening the door, because in the past doors have jammed in the frame and prevented the pilot escaping a fire. That's why a lot of people are calling it out as suspect that he has his door open a bit from the very start... like he already worked some kind of precautionary landing checklist. Forward-hinged doors are also hard to open in flight because of the air pressure on them (that's kind of a feature), so one also wonders if he had tested to make sure he could get it open enough to fall out.

It's hard to believe that someone with a certificate wouldn't at least promptly fumble for the checklist, and I bet inexperienced pilots would probably be inclined to make a radio call earlier than experienced ones did since it takes some discipline to keep your priorities on aviate, navigate, communicate when things go wrong. Yet we never see him make a radio call at all, which is very odd since he expresses concern about having a way out of the mountains... I personally suspect that he knew that a mayday call would probably result in a fire brigade or sheriff's deputies or state police helicopter or whatever showing up before he had much time to address the crash site (controllers activate local fire and search and rescue as a precaution when they hear a plane might go down in the wilderness and it didn't look like he was that far from civilization). That could easily lead to questions and discovery of evidence that would become a problem for him later, so I think it was an intentional decision to avoid having authorities notified in real-time. This is a cynical take obviously but it feels like he was preserving his ability to tamper with the incident site before anyone showed up who would know to preserve it for investigators.

2: I mean it's hard to say about some random airplane, obviously it's a very old aircraft but most of the critical parts will have been outright replaced much more recently than it was made. The FAA has requirements to keep an aircraft in use and they involve regular inspections and preventative maintenance, so older planes don't tend to fall out of the sky just because they're old. There are ways to skirt these rules but not a lot of them, and if it's found that he did (or the owner did or whatever) he will really get the book thrown at him just on that front. For the most part if an airplane is still registered to fly it's in as good of mechanical condition as any other plane, although sometimes older aircraft will get relegated to basically experimental status because of missing safety features (which puts in place restrictions like not flying over cities). The Taylorcraft he was in is certified as a standard aircraft though, nothing weird going on, except that I think it might fall into the grandfather sport pilot rules that allow certain standard aircraft to be called "light sport" if they meet the requirements but were certified as standard because the light sport class didn't exist yet at the time. That raises the question of whether Jacob had a sport pilot license or not since that program gets some criticism from a safety front, but from searching the airman registry it looks like he has a regular private certificate issued about a year and a half ago, on a third-class medical from 2018 which suggests maybe he started and stopped training but isn't super unusual.

Also what YouTuber in their right mind leaves the part where they say "mayday mayday mayday" out of the video. It's just like the movies! If we believe that he worked the steps and just edited them out, it's a really bizarre creative decision for him to make. Hard for me to believe.