First of all, assuming all of what we observe can fit with your flat earth model, wouldn't this mean that the FE model and the round earth model are equally plausible?
(Explain what makes the spherical earth model implausible......)
Now for specific FAQ questions...
Q: "Why are other celestial bodies round but not the Earth?"
A: When you look at these celestial bodies, even with a telescope, they're entirely two-dimensional.
if a person in Indiana looks at Jupiter, and a person in China looks at Jupiter, they both see a circle. if Jupiter was a disc, in order to appear a circle to both of them, its center would have to be facing both of these people at the same time, which is impossible. perhaps the planets are spherical but the earth is flat?
Q: "Why does gravity vary with altitiude?"
A: The moon and stars have a slight gravitational pull.
but you said that the moon, stars, and earth, are all being pulled upward by dark energy. so perhaps you mean to say, the moon and stars exert a slight anti-dark energy force, causing there to be less upward acceleration at higher altitudes?
but still, why does this dark energy push the earth and sun and stars and such upward at this rate, but not the objects resting on the earth? (if everything was pushed up at the same rate, there'd be no 'gravity' that we could feel)
Q: "Please explain sunrises/sunsets."
A: It's a perspective effect. Really, the sun is just getting farther away; it looks like it disappears because everything gets smaller and eventually disappears as it gets farther away.
this completely ignores basic understanding about perspective. a disc orbiting around the equator of another disc could not appear to move below the disc