Heya, congratulations for your achievements!
Being myself a flight simmer since 40 years and formally graduated in aeronautics, I have long forgotten the sensations of the beginnings and I can assure you reading your post has been much refreshing and interesting at the same time.
If I can add a comment to your well thought analogy:
“The best way I came to think about it is buoyancy. The plane is like a submarine in water. The more water (less thrust) the less bouyant you are and the more you sink.”
Actually this true for aerostats (balloons and airships) whose lift is indeed provided by bouyancy as they are filled with lighter-than-air gas (typically with inert helium, in the past with the extremely flammable hydrogen)
For aircraft, the main factor that keeps is flying is its speed in the air.
Aircraft speed is controlled by aircraft attitude and engine thrust.
Two example conditions:
Leveled flight → more thrust applied → more speed → more lift
Climb flight → less speed → less lift → more thrust is needed
Every aircraft of any type has its characteristics reference speeds:
stall speed (with flaps or not)
takeoff speed
cruise speed
max maneuvering speed
never exceed speed
The list is not complete, still these are the ones most important.
By knowing these speed for a certain aircraft, irrespectively if its a big jetliner or a jet fighter or a propeller driven leisure plane, you will be able to jump in the seat, fire up the engine and take the sky with safe and ease (well almost 
) by assuring for every phase of the flight your speed will be the right one.
Hope you appreciate these small hints, have great fun with flying!