We sometimes lose planes and things of that nature but Earth is a water world and we don’t have a level of technology to break out of our stellar system faster than four decades. The Empire have much better technology than that and they are looking at a almost uniform sand ball.
We have no idea how long the droids travelled with the Jawas, though it would be nice to think Artoo had a hand in sending them off to the Lars farm (which he still remembers) either by hacking the crawler or persuading the Jawas of the potential profits (in the radio drama version he deliberately sabotages R5D4 so that Owen buys him instead so it’s not outside his behaviour type to do something like this).
The Death Star seems to be only able to destroy solids (rocky planets, metal spaceships). Destroying Yavin may have been beyond it’s design parameters.
The Death Star is the size of a small moon but how much of that is habitable space is not explained. A gravity train travelling through an Earth sized object would take about 45mins to travel pole to pole. The Death Star has less mass and is mostly hollow but a powered elevator would do the job even faster. One assumes there is some sort of transit hub on the station so it may be a matter of changing elevators a few times. A bit like using an underground train system only a military one without all the annoying gits with ice-cream making machines getting in the way.
It’s a two meter, ray shielded port on a top secret battle station surrounded by laser turrets and guarded by waves of fighter craft and this from a designer who doesn’t expect a small scale assault (it almost doesn’t work). The only other pilot to get near enough to fire (at the expense of his squad buddies) misses and gets himself blown up for his trouble. The elite bombing squadron is all but wiped out in the first attempt.
Star Wars has some little leaps into the coincidental but they are much fewer than TFA not unless there’s one all-powerful force controlling everything.