It seems you have studied music at an advanced level. I can tell that maybe the advice I can give will be easily communicated, but I hope I understand your question correctly.
I tell most people that want to know about the guitar as the first thing: You have a pinky, use it. lol.
When changing chords it is often the most difficult challenge to change without making noise on the strings. The best technique to avoid this is to practice lifting your hand from the fretboard and placing it correctly on the next chord. Especially in dealing with classical playing, you will have to utilize proper positioning of your hand. As you may know there are 3 octaves on the guitar. Remember that you can utilize these notes effective from any position. For example... 5th fret on the B string also the same octave as the 9th fret on the G string. So when reading notation depending on what chord you were playing before hand, you will know the easiest route to tonality.
It is like playing pool, you have to set up your next shot. So by lifting your hand off of the fretboard, you are training yourself to be more cognitive of your flexibility and reach, and also reducing fret noise.
Your nails are a good thing.... on your right hand at least. You will need them for volume and tone. lol..... Your left hand, I would advise trimming. Else, maybe the steel guitar is an instrument best suited for you. :P lol j/k I can't say with confidence that I have met any classical guitarist that can play effectively with long fingernails on their left hand. I have seen stranger things though, so it may be true somewhere in the world.
Using bar chord techniques will help you a lot. When reading the notation, you can identify the octave and position you will need to achieve proper tonality, and the bar chord is the right tool to allow your hand the freedom that it needs. Try first by identifying the root and creating your bar chord from there.
If you want to talk more about it, I would be glad to offer any help I can. I can show you many examples of using bar chords effectively to cite classical musical notation.
I hope that I have helped in some way,