Is there for every $k$ a $k$-connected graph whose longest paths do not have a vertex in common?
This is known to be true for $k\le 3$, see
Ayesha Shabbir, Carol T. Zamfirescu., Tudor I. Zamfirescu: Intersecting longest paths and longest cycles: A survey.
Surprisingly, nothing is mentioned about $k\ge 4$, though the question kind of appears on p. 232 of
Tudor I. Zamfirescu: On longest paths and circuits in graphs.
Some related questions include Hippchen's conjecture (any two longest paths intersect in at least $k$ vertices in a $k$-connected graph) and the problem of determining the minimum size of a hitting point set for longest paths, about which there is a recent MathOverflow question.