One possibility for some of the answers is that the guy scoped out a good hide, checked it for sight lines, concealment, and awaited notice. But, still, that’s twelve hours in which time you have to pee your pants while hoping your contact was correct. Could have gotten an eight-hour nap and a Big Mac to go.

On the second question, I’ve only seen reports that he decided late enough that it wasn’t on any released schedule; however, it had to be early enough before-hand to contact his friends and get a tee-time (I’ve seen speculation that other people were cancelled to make way for him & security, but no news reports on that AFAIK), so it could have been anytime on Saturday or fairly early on Sunday morning.

On the first question, see this:
https://justthenews.com/nation/crime/alleged-shooter-hid-nearly-12-hours-secret-service-saw-him-golf-course-prosecutors

The cellphone of the alleged would-be assassin pinged on the edge of the Trump International Golf Club in West Palm Beach, Fla., starting at 1:59 a.m. on Sunday, per the federal criminal complaint, The New York Post reported.

The Secret Service saw Routh’s gun at 1:30 p.m., when he was about 300-500 yards away from Trump. Routh also had a video camera and two backpacks in the sniper’s nest.

If Trump made the decision on Saturday sometime, even early in the morning, then how did Routh find out about it? He doesn’t seem to be in the inner circle of Trump’s golf buddies and the golf excursion was not on a publicly available schedule.

If Trump made the decision Sunday, then Routh was already in place before the golf date was set up.
Precognition, however, doesn’t seem to be something Routh is known for.

Why would he go out “on a hunch” at that hour of the morning, and take a huge amount of compromising gear and illegal weapons (for a felon), on the off chance Trump would be there sometime during the day?

Regardless of the time Trump’s decision was made, and how Routh knew about it,
when did he plan all of this? His set-up was far too elaborate to be a spur of the moment operation, when he would have had less than 24 hours (from Saturday morning at the earliest) to pull it together.

My other question (and I am not alone):
How is it possible that nobody saw him lurking for 12 hours along the fence that was, apparently, close to public spaces?

Maybe it was dense enough brush that he couldn’t be seen: how did he know that would be the case? How far in advance did he scope out the golf course?
Of course, there were fewer pedestrians and drivers on Sunday morning, but that’s a chancy thing to count on.
Did he never go to the bathroom or eat anything for 12 hours?
Did he just sit or lay there, waiting?
What if he had dozed off and missed Trump’s time at those holes?
What was his plan if someone had seen him loitering, especially with a gun?

As for the security guard:
After the mockery of the Butler Protocol (“we only shoot after the perp opens fire”), the agent was right to respond to seeing a rifle barrel through the fence, but how did he see that it had a scope (assuming that report is correct), if the brush could hide Routh for 12 hours?
If he actually could see the scope, he should be able to see Routh, or have a good idea where he was, so how come the USSS agent didn’t hit him when he opened fire?
What if someone else, an innocent by-stander, had been in the area and had been hit by the agent’s missed shot?

That’s not the totality of the loose ends that any fiction writer (book or movie) would have to sew up while putting the plot in order.

None of this makes any more sense than the first assassin’s “lucky coincidences.”
Except for him getting killed; that was unlucky.

Perimeter patrols anybody?

Which explains the tenor of his dismissive statement i.e. of course such a “candidate” as ex-President Trump did not merit a full security detail.

OK, done with the firearms stuff.

Steve: the RPK is a light machine gun on the Kalashnikov action. It also shoots the 7.62×39 intermediate round. As you say, not suited for sniping. I’ve shot the 7.62×54 round in a Soviet SVT-40 and a couple of Finnish Mosin-Nagant rifles. It’s a slammer–and very accurate in the right rifle.

Yes, Dragunovs have been used in Ukraine. Routh may have come across them there. I read somewhere (the indictment?) that he has been charged with owning/using a firearm that had the serial number removed–a felony even if he had possessed the rifle legally, which he didn’t. Add that sinister little factoid to the ceramic bullet-proof vests and the GoPro camera, and this business has a nasty whiff of professionalism about it. I’m not saying Routh is a pro; I’m saying he may have had help or guidance from one. Given Routh’s connections, possibly Ukrainian. Again, speculation on my part. I hope the Florida investigation is thorough.

It should be very obvious, by now, that Trump’s enemies within the Biden Administration are denying Trump the very robust security he so obviously needs, in the hope that he will be killed; the huge threat he represents swept off the board.