Great analysis, let's run this down.

First, the cruise missiles aren't necessarily fired from Russia. MOST of the cruise missiles fired in the war have been fired from the Russian navy, ships in the Black Sea, so the missiles would be coming from the S or SE.

Cruise missiles do not fly straight to their targets. They are programmed with routes that wind around known AA and other troop concentrations, as cruise missiles can be shot down by alert manpad teams watching for them along expected routes. We have seen video of them doing this. So the missiles would wind their way to their targets, and, as long as they aren't sufficiently detected or engaged, no one minds if they take an extra 40 minutes of flying time to reach their targets.

2 - No, the S-300 missile would fly most of its range unpowered. The solid rocket propellant accelerates the missile to mach 6, then then the missile continues to engage its target for as long as it has enough energy to stay in the air. If it misses its target, either by failing to successfully lock on target after launch, or missing the target, the missile will fly straight if it doesn't find any new targets.

The S-300 missiles are "command-guidance system" which means they are actively fed target information from the central radar station for the first 25nm of its launch, meaning that the missile is on its own if it misses the target. If there is a guidance failure (missiles fail all the time for various reasons) the missile would just continue until it runs out of energy and fall. It does not have a self-destruct mechanism.

3 - Ukraine is referring to the cruise missile threat, correct. The missiles came in a wave

Haha - rocket science - yes, these are rockets in the traditional sense. That's how they are so deadly. The rockets are actual rockets, and they go fast, FAST. They hit mach 6 within 25s after launch

I personally don't believe the missile incident would have had to happen timed perfectly with Trump's speech... just in the few days. They run so much media, they could push this if it was within a few days, IMO

Just my two cents, but, I know these systems and how they're deployed/used on the battlefield intimately.