Submarines are still in Testing, and Homing has being adjusted over the past several patches. Please expect changes and iterations as testing continues.
If you are having trouble with being too close to use Homing, perhaps switch to the Dumbfire option and lead normally?
These are all things employed in the process of Balancing.
Battery Depletion has no realistic tie to being Detected, but it allows for Detection to be a slow, constant problem for a Submarine. Due to the capabilities a Submarine has in regards to staying undetected, Surface Ships having additional interaction capability is part of the back-and-forth of gameplay.
You have expressed your dislike about Operational Depth not having self-spotting. However, encouraging a solo Submarine to Periscope or Surface Depth makes them more able to be interacted with when detected from sight, hydro, or radar. Depth Charges impact Submarines at Depth, but forcing a Sub to surface makes it vulnerable to shellfire before it can dive.
As a Sub still receives Team Spotting at Operational Depth, the Sub Driver can elect to operate in/around allied ships
Submarines can be RPF'd at Operational Depth because this is a Game. While Radio Location is a thematic name that a player can intuit, the Game World is a Game World.
Gameplay Interaction shows that RPF giving information on a Sub's position is workable, and the Sub can go to Maximum Depth to avoid RPF if it wants.
Initially, German Submarines were treated as the close-in knife fighter Sub. However, due to a lack of rear Torpedoes on the Tier X, the concept was switched during our testing... and is still under testing.
As for the power of the German Depth Time Consumable in forcing a US Sub to the surface, you are correct. US Submarines are more vulnerable in this sense and would be best played with allies nearby that can assist when hunted by an aggressive German Submarine. This is a play condition that a US Submarine accepts on entering battle and should be wary of getting caught by.
At Tier VI, you would be advocating for a 5 knot underwater speed, and a 35 knot surface speed.
At Tier X, you would be advocating for a 20 knot underwater speed, and a 40 knot surface speed which is faster than some Destroyers.
Subs already have an ability to disappear from RPF and all forms of non-Sub spotting by going to Maximum Depth. What is the need to outrun some Destroyers as well? Also, while 5 knots may seem a reasonable number in terms of a historical concept, the play experience would be extremely awkward.
Part of having multiple Classes to play, and multiple iterations of each class is to provide a variety of gameplay options. If you are looking for something faster, you should certainly consider playing a Destroyer.
Detection is artificially large for reasons of Gameplay interaction
Feel free to suggest Captain Skills you feel are balanced and worthy of replacing the existing ones.