I also get the explosions and fire in space - fire needs oxygen to bure granted when a ship expoldes oxygen withing= the ship ignites...
No, that wouldn't actually happen at all, since the air would dissipate into the vacuum almost instantly with no time for any combustion to occur. Not to mention that the roiling, cloudy effect of a fireball explosion happens because the flames are mixing with air, so even if it did happen, it would look entirely different if they were expanding into vacuum, more just a smooth expanding bubble.
"Fireball" explosions in space scenes -- or really in most scenes in film and TV, period -- are a filmmaking conceit that has little to do with what most types of explosion would realistically look like. As a rule, the more powerful the explosion, the less flame you get and the faster it's over, because the reactants are either quickly consumed or quickly blown apart. Special-effects artists prefer liquid-fuel fireballs because they're low-energy eruptions, which means not only do they pose little danger, but they have more bright flame which looks cool on camera. Most of the kinds of explosion they're used to represent, whether grenades, C4, building demolitions, natural-gas explosions, or whatever, look a lot less fiery. (As any loyal viewer of
Mythbusters should know.)
Of course, an antimatter explosion like a starship warp core breach is far more powerful and would be over in a split-second. There'd just be an extremely brief, blinding flash and then the ship would be completely gone, replaced by a diffuse, swiftly expanding bubble or spherical cloud of gases (and maybe some debris, if the reactants flew apart quickly enough to stop reacting before the ship was entirely consumed).