2. Doesn't Steve going back to have a relationship with Agent Carter impact the Timeline. Heck, the Orville just did something to that effect, how a choice we make impacts our lives. So Steve goes back to the 70s, has a relationship with Peggy, does this mean he's not captain America? The other Steve is Frozen so this Steve basically doesn't exist and that's how nothing changes?
No. Steve's final journey is to go back into the past. It was always meant to happen.
Frozen Steve will wake up and go through all this again and then finally end up in the past.
Also
