how to play in coop with a friend without being restricted to 2 flasks and not being allowed to open bonfires

Hi, so couple of questions

1) Is there a way not being summoned as a phantom with 2 flaks and not being able to progress your campaign, maybe something like completely normal coop walkthrough?

2) how do you sustain summon signs? just farm yellow flowers without stopping?

3) for example my friend opened stormveil and asks me to help him out with the boss, i went straight to caerlid and dont have bonfires in stormveil, can i help him somehow, or the only his option is to summon random gold phantoms?