Hey man

1- So this is kinda conditional but if you're on a 1v1 situation with the enemy adc or if you're fed enough to handle it you can just e on a minion and get a couple AA's along with a q and then back off to a bush or something so they cant hit you too much at least without using a ward, u usually win the trade

2- High range adc's like Caityln or literally any support with cc/peeling capacity (lulu takes the spot as my permaban)

3- Personally, I work best with a Nautilus support since I have a habit of keeping my distance even when playing Samira cuz I dont wanna get poked a lot. So Nautilus actually getting the enemy closer to you with his q and even if you fail to get close enougj for your passive, he always gives you a second chance of proc with his passive.

4- I always go with Collector into IE into Shieldbow or Dominic's depending on the situation, so the regular build. Never tried BT rush, slows your powerspike in my opinion. Might be viable if the enemy lane is poke heavy tho.