You make the bubble after you are already moving in the direction you want to go. The bubble will keep moving. What else would it do? Out of all the questions, this is not a hard one…
In relativity, observers only agree on motion at exactly c, so the idea that a warp drive speeds up normal motion… feels like a contradiction.
But then, I know I can't fully grok the relatively simple maths of SR, let alone GR.
You get it!
If you have to spend the entire combined annual energy output of all of humanity getting up to speed, why convert the equivalent of 1% of the mass of the sun into energy to create and maintain a warp bubble?