Well, that's gonna be a lot of typing. Can't answer everything, plus, it's hard to explain without visual aids. I started by watching videos until I could grasp the concepts and do it myself. Yes, looking for the curve, super easy to see, but difficult to understand what you're seeing because of the programming, we have a hard time accepting what we see. If you look across a large body of water, and you know the distance between you and some buildings on the other side. Then you can calculate how much curve there should be, and then you use binoculars or zoom camera to see the bottom of buildings that should not be possible. Refraction is the excuse people use, but that doesn't explain how you can see a perfect clarity of objects that are supposedly behind a curve and don't have direct line of sight

So, using trig. You can observe the sun or moon. You and friend. The concept is best visualized when you're several times zone apart.

You have to know how far apart you are. The base. And each of you take a measurement of the angle of the moon from your horizon.

What you will find is that you can use those angles and the known distance to approx the elevation (height) of the moon. It works. But if you assume there is a curvature, then the angles don't make sense because it would mean there are two moons, the single object could not convervge with the angles you observe. Really hard to explain on text.

As for tides. So, there are 4 tides per day. But not everywhere. If the moon was causing tides, then we would have two tides every day. Think about it. Also, tides would be everywhere, but there are tidal nodes all over the world.... places where the ocean doesn't change tides. The globe tards struggle and jump through whatever hoops they need in order to keep their beliefs alive, but when you look at a tidal nodes map, you can see there are just too many places that are not affected by tides. The moon and gravity supposed to be consistent, so why some places not affected?

Gravity is not a force and doesn't exist. It's just magnetism and boyanct forces at play. Gravity isn't needed for any physics calculation, because you can just use acceleration. Gravity is actually just an observation of an average rate that things fall. It's a man made concept that hides the actual forces at play.

I don't know how this is gonna work. I'm not trying to convince you. I can answer questions, sure, but you have to have some momentum of figuring it out yourself first