No, yes, and no.
Student or Learner
If I say "I used to play tennis with Bill at high school", does it necessarily mean that I don't play tennis with him anymore? Could it mean that I still play tennis with him, but we're not at high school anymore? In the same way, if I say "No, I didn't use to go to Boston when I was young", does it necessarily mean that I go to Boston on a regular basis nowadays?
No, yes, and no.
I am not a teacher.
It’s certainly true that “used to” often implies “but no longer” but it’s more of a pragmatic consequence than a semantic rule. “Used to” can only refer to the past, and why would you use a construction that only refers to the past if the thing is still true?
If someone came up to me and said: “I used to play tennis with Bill at high school.”, I would conclude they no longer do.
But now suppose you asked someone: “Did you play tennis when you were at high school?” And they answered: “I used to play it with Bill”.
In that case I would not conclude they no longer do.
They might elaborate by answering: “I used to play it, and I still do”.
But this is a type of instance, where we are clearly talking about the past and the information about the present is a kind of afterthought, is the only one where I can imagine using “used to” with “and still” rather than “but no longer”.
Ordinarily, you would elide the past and present by saying: “I’ve always liked playing tennis with Bill”.
However, these are only speculations and you might easily disregard them, beachboy.
"I used to play tennis with Bill when we were in high school."
The preceding sentence refers to a specific circumstance. In fact, the sentence itself states that you are no longer in high school. If you said that you used to play tennis with Bill you would be saying you don't do it anymore.
(You might want to use a separate paragraph for each question.)
Note that in AmE we say "in high school".