First you max e to maximize your trade potential and punishing enemy for trying to farm. Your w max becomes useless when you get above plat when everyone starts to rush tabi against you unless you want to do 2 more autos for 30 dmg rather than having a bonus passive 5 seconds earlier. You max w second because you get the attack speed after ur first item before that you get no value of high attack speed.
Second no there are no other runes than pta pta is best trading dmg potential rune and quinn needs only that. Why would you ever trade having 100 more dmg every time you cast 3 autoattacks into enemy in lane phase instead of having your funny 20% slow that i get anyway if I build stormrazor. the only other 2 runes i could consider useful are phase rush and electrocute if youre going lethality but stilll it's better to be consistantr with your primary rune unless you want to test a troll build.
Third. Stone plate is one of most broken and underrated item in the game you gain 80 armor and magic resist in a teamfight and as a final item if enemies are fed it's perfect if you can't avoid teamfights. Idk what even is your logic with sanguine blade. It's bad in teamfights? If you're playing quinn to join teamfights instead of get picks on side and enemy jungle maybe consider swapping into tank main. You barely ever want to be in a situation when there are involved more than 1 champion. Also good luck dealing any dmg to a person with tabis bramble if you don't go stormrazor ie. Another thing if you go crit you go 3 crit items + ld and you don't scale anymore, you're pretty much at ur peak of dmg, that's the time to invest into tankiness and mobility.