1. Which ADCs would you recommend in 9.4 and why?
I normally just play what has good winrates atm because that gives u a good basis to work with if u want to get strong ingame. If u are in higher elo go for draven lucian to not fall too far behind and snowball games from the start. If u are in lower elo and games go long because people dont take objectives take stuff like sivir, vayne, jinx and just scale and collect gold.
If your Support is bad and for example a Thresh, can't hit a single hook (we get outpoked by ezreal, brand) and is pretty much completely useless (maybe also dies frequently) What exactly should you do as ADC ?
Well u cant do much as an adc early if ur sup runs it down. Avoid fighting let them push and maybe even go roam urself if the lane is unplayable and surrender ur first turret. But u cant win every game and if ur sup runs it down it gets hard as adc.
When ishould all in with championslike Syndra LB Zoé Ahri? Just farm, try to poke , stacks manaflow, wait item, try togo in when no big wave and i can do my combo ( normal lane and me i can w q e or smt like that or try to e and qspell with zoé) ?
U all in when u have a high chance of killing them so u either have more people like ur jgler comming etc or u are higher lvl and hit lvl 6 first or basically any lvl lead. I avoid fighting if i dont have an advantage and just be patient they will fuck up soon enough.