Two questions concerning targeting/ torpedo control using manual TDC

[Spraug]

Hi,

again a some questions for a better understanding of weapon control in my american campaign. tIt's he first using TMO 2.5 and 100% realism - should be less, because I can't live without the map contacts, though I only use them for awareness (especially radar and sonar), not aiming. Anyway:
1) It seems that I cannot just lock in a bearing with my periscope and send the torpedoes that way, right? Do I also have to lock in range or do I always have to "L" a target?
2) The TDC allows to deviate torpedoes to the left or right of the aiming line. Do the degrees on the TDC match the "degree dashes" on the periscope? So that I can aim for "three degrees left of the aiming line is the bow turrets' magazine, yep, that's where I want you to go."

Thanks