Yeah, in some days I'll play my first scrim with some friends and as a medic I'm trying to learn some strategies on popular maps like granary and fastlane and also some tips to go better

I was thinking if you could help me
I'm not sure but I think the lane of the other team is 2 pyros 1 scout 1 medic 1 demo 1 soldier (lol)
I need to find a way to counter those pyros in close spaces like granary point 2 and 3 (?)
we're going on the popular 2 scouts 2 soldiers 1 demo 1 medic
and should I stick with only 1 soldier (or demo) and heal the other when they come to me or should we go as a block and let the scouts go free
Who should I priorize on healing?
sorry, I know theses questions were already answered a thousand times but it's our first scrim and we want to start winning

PS: sorry for my english, I'm brazillian