Getting in on the Gravity Bomber, this is my read:
- There exists artificial gravity in (virtually?[1]) all craft.
- This pervades the whole 'shell' of the craft, by design, including any bays with atmospheric force-field separating the insides from space[2].
- The 'bomber' uses this effect to 'gravitationally eject' its bomb-load 'passively' without the use of active projectile/missile propulsion that (maybe?) is more detectable or counterable[3] under *hand-wavy* in-universe technical limitations.
An alternate explanation is that only these bombers, with their 'cartridge' bomb-rack units, have a good enough carrying capacity vs size to be considered able to accomplish the mission (amongst all vessels available at that time).
Plus, the concept of 'orbits' is fairly unknown to 'Wars. It's arguable even if that's the real reason for the slow approach of the DS around Yavin to target Y4 (*hand-wavy limitations about reliably hyperspacing directly to accurate points within a gravitational system*[4] ) and not just a sublight movement from an obscured position to a firing one. The 'shield gate' above Scarif (Rogue One - and I'm sure they pinched that idea from Spaceballs: The Movie...) seems to be 'geo'stationary, but
not (making assumptions about planetary rotation speed) actually at geosynchronous orbital height. Ships and stations seem to have a habit of ignoring orbits[5] or gravity almost at will, and planetary gravity
without centripetal orbital out-fling in exact opposition would give further (reduced, compared to surface-level) gravity to further accelerate the bombs once released.
...but that's just my head-canon as to why these tactics apply in these circumstances (and not some of the more obvious ones, like as mentioned or alluded to in the footnotes bow, especially). I agree it's quite silly 'IRL', but republics and empires and confederations and the rest alike, that long ago and that far away, seem to mostly stick to paradigms where Hodor Manoeuvers are the almost unknown exception and far from the rule, and battle each other on the almost blinded assumption that their opponent is using the exact same philosophy, give or take a Super/Megaweapon or thres...
[1] No reason to believe it doesn't exist in single-seat fighter cockpits, like Ties or *-Wings. Unless any EU material ever depicts floating things/bodily fluids, and even then that could be an AG failure, not the total lack of it. It's probably even adjusting (or automatically self-consistent, regardless of the external forces) to allow those high-G, negative-G and torsioning yawing and rolling manouevers to be undertaken by pilots, much the same as the Inertial Dampeners in the 'Trek universe. The skill to flying might be more about how to 'feel' your movement properly and fly by the seat of your pants when you have no direct personal inertial cues (apart from momentarily undampened vibrations from micrometeorite impacts or atmospheric turbulence, whenever they happen).
[2] Must check footage of (say) un-forced docking of ships in Death Star-like landing bays to see if they assume the
ship is weightless to space, but then has to 'hover down' onto its landing gear once inside, and how they transition (a firm limit boundary passing across their body as they pass through the air-bulkhead, or a gradient, or a lobe extended) but this might be complicated by tractor-beam technology automagically helping the 'raw' transition.
[3] Ship propulsion, and in-ship inertial/gravitational fields are somehow less un-stealthy than projectile or missile launchers. Because. (The 'submarine scene' with the Falcon gone to ground in the asteroid 'cave that isn't a cave' comes to mind as a time when they even hushed their voices, at least temporarily, but that could be more psychological (in-universe, as well as filmically) than practical.)
[4] Or possible tactical reasons in case the planet-killing not-a-moon should be sufficiently wary of not-a-moon-killing weapons possibly fired directly from the moon-planet, even for the highly over-engineered defences of the DS. Before it is more locally scanned and deemed militarily safe according to standard Imperial military doctrine.
[5] There is no sign (that I am aware of) that any sneak attack upon an 'orbital' installation was ever made by taking heavy/explosive projectiles to the antipodal point from the target and boosting them away over any/all possible intersecting orbits. And near-intersections, to catch any attempt to move the target out of the way of any detected incoming threats, perhaps even deliberately made detectable and set to 'herd' the installation into the zone the true destruction will rain upon. And setting a small but deliberately 'stealthed' (painted and/or shielded) asteroid in counter-orbital collision to a target might be a very good stood-off attack vector, compared with sending a crewed vessel in at virtually 'docking speed' in a near-suicidal deliver-then-depart bombing run.