well, nothing really ever goes up because there's just nothing there. as for reaching the oort cloud, you could travel in ANY direction and reach it
also, nothing really heads straight from planet to planet, usually satellites will follow an arched path due to being literally slingshotted out of
the earth's, moon's, or other celestial body's gravity.
as for the astroid belt? well, we've gone through it plenty of times. think of all the probes that have visited the jovian worlds. the asteroid belt
is nothing like what you see in movies.