An upward moving object must be experiencing (or at least usually does experience) an upward force? true or false

That's false.  Think about a stone or a baseball, during the first
several seconds after you tossed it straight up, before it reaches
its maximum height and starts to come down again.
There's no upward force on it during that time.

Also, after a roller coaster reaches the top of the FIRST hill, there's
no upward force on it for the whole rest of the ride, even though it
coasts up many more hills. 

Because the dept in the ocean

That depends on what kind of environ meant it is in  in space it has the same force that was applied when the velocity was gained