Microphone not working for team but works for group

I searched but didn't found anything about that in the conf'(and I had already looked for any settings that might be useful) or on the web. You can overwrite the chat push to talk for each heroes but it's not done for groups. So, I don't think it is possible. I suggest you to make a request about that because it would be useful, the dev' team totally understood the necessity of overwritten keys, and would probably add this in next patch or in few ones if you request it.

PS: This is not relevant, and you probably already knows it but press P to go to channels selection faster.

My favorite hero to play against multiple turrets is Junkrat. He can launch his grenades into hard to get to places and deal quite a lot of AOE damage to help push a Torbjörn off from repairing his turret and to destroy it. He can bounce them off walls into room where turrets are setup, or launch them far enough to hit the turret over a wall at the turret from relative safety. Killing Symmetra turrets is a little harder with Junkrat, as they generally aren't on ground level, but if you have a tank or healer with you, it is a bit easier to clear out rooms.

Another person who is pretty good is S76. He has pretty solid mid range damage, and if he has a tank, he can usually pick off a Torb turret with a helpful rocket after shooting it a bit. He also can drop a health pack for himself to help tank it if he is alone.