Re: 1701 warp core?
I always thought the tube-y thing in TWOK was the dilithium crystal housing. Would be a pretty good locale for all that radiation (lotsa it from m/am reaction), so the reactor would occupy the space below the engine room thar. I've always thought of the TOS/TMP reactors as being rather large and rather oddly shaped, with lots of sprawling support equipment and what-have you, unlike TNG's lawnmower-motor-sized reactor (by comparison, anyways).
STAR TREK: 1964-1965½, 1966-1969, Jan. 21-23 1972, 1979-2001, 2003-2005, 2009-?