So, if I'm understanding you correctly, the earth, the people on it, and the heavenly bodies are all attracted to one another gravitationally, by the virtue of them all having mass. You yourself (and many FE folks) have acknowledged this. So, what keeps the earth from colliding with these celestial bodies? The earth is accelerating upward toward them after all. Are they also subject to UA? In fact, the celestial bodies must actually be experiencing greater UA since they are able to outrun the earth's gravitational pull. And if they're accelerating faster, they are bound to move away over time.
This brings me to a point I forgot to mention earlier: if all observed gravitational acceleration on earth was the result of UA, the earth absolutely would rip itself apart as it rose. You said that you see no reason why this would occur, but this is a basic property of acceleration. Different acceleration by definition means that over time points on the surface will achieve unequal velocities, and unequal velocities implies that the two points will not stay near each other as time advances, ergo the earth would need to tear apart to accomodate all these differently accelerating points.
As for the final matter, I greatly respect and admire your desire to discover the truth. The relationship between scientific inquiry and truth has a long and messy history, and is probably best left to minds greater than ours. The greatest quagmire seems to be that no amount of positive evidence can ever, with certainty, prove a theory true. Of course, it is comparably easy to disprove a theory-- all that's needed is a counterexample. Hence the scientific method: the aim is always to disprove a null hypothesis, rather than to prove a true one. There is confirmatory and contrary evidence for both FE and GE, and depending on who you ask, both theories are capable of dealing with the contrary evidence (I'm granting you a huge concession here by the way). The only real difference is that GE is a very simple explanation, and has amazing predictive power, and FE theory is extremely complicated and has not yet advanced to having the capabilities to make solid predictions (of the sort made by GR). Most conversations I've had with flat earthers that got this far resulted in a stunning rejection of the premise that FE theory was "extremely complicated," but this is exactly the case. At first, it seems much simpler, but then you have to factor in something that explains the movement of the stars, and gravity, and the ether, and jovian moon orbits, and seasons, and whatever science discovers next year, etc. And you can do it, don't get me wrong. It's possible to believe in a model that just adds another entity to explain any stray phenomena, and you can do this ad infinitum and still have a valid theory. The theory wouldn't be "wrong" in any way. My question to you is: does that theory look like truth?
I had a philosophy professor who used to insist that he believed that instead of gravity, matter in the universe was pushed around by invisible gremlins. It is, as we learned, impossible to disprove this, especially when the interlocutor is free to speculatively invent new pieces to the theory (ie, something that explains gravitational waves) as he goes. It's pretty clear to me that although this model "works," it is almost certainly not true, simply because it is equally as likely as any other model for gravity which lacks evidence (UA). In the end, we're free to believe whatever we want, but know that Globe theorists have the unique advantage of (copious) evidence. I'm unclear why you would bet on any other horse if you were looking for truth.