Lane Match Ups and Team Comps Questions

Hey everyone,

I play support I have a few questions about the title topics if anyone can answer it would be hugely appreciated!

1. Choose synergy with your adc or counter the enemy bot lane? poke>kill>sustain.
2. Choose a champion that works well in lane or in your team comp?
3. I have a basic understanding of team comps but in soloq no one coordinates their picks. At what point is your team considered a _________ team comp? I've also heard to just play champs that are good in teamfights because that's what happens in low elo anyways?

I know these are things I'll learn as I go but there are so many variables I thought maybe someone could explain their thoughts or provide some good links so I can learn it quicker. :)