I compiled the main points of your distrait posts into this:
Hey Guys! I always knew how to read sheet music... Currently, I'm playing with a 64 key digital keyboard.
What I like to play are Disney songs, songs from movie soundtracks or video games.
That is fine. I play a cross section of everything from 1750 classical to 2011 anime. You can learn to play in a specific genre; the key is to start playing things that you have a desire to play and a passion to learn. Later on you might expand outward for various reasons. This piano forum has all sorts--not just classical piano students.
Here is my problem:
I'm trying to get better, but my skills are so scattered.
I can read the notes, I understand treble and bass clefts, but I start to have problems when I have to play 4-finger chords and a melody with my left hand.
Define your skills. Make a list of what you deem necessary to a skill set. WRITE IT. Make a list. it should be something like:
4) Finger span and fluidity
5) Range of expression
Rate yourself on each point. Then go forward and improve on them. If you need timing help--use a metronome; if you need reading skills--spend time reading and playing tons of new pieces you never saw before; etc.
I assume 4-fingered chords in Disney means arpeggiated chords? Or are they harmonic (all notes at once)? You should go repeatedly over difficult sections and try again and again with both hands or single hands to make it work. You'll find that these early problems evaporate with time and effort, even if they seem ridiculously difficult now, they will seem ridiculously basic in future.
I'm trying to find sheet music that matches my level (whether it be beginner or intermediate...etc, but my skill set is so scattered that I have no idea.
I'm just trying to figure out what my "skill level" is, I don't know if that's useful when looking up sheet music.
That is always a vibrant topic. The answer is... there is no serious answer. Those "levels" they assign academically or within publications are a mixed bag of subjective labeling. They are made by unrelated people making their own approximations.
Beginner is obvious, though. Advanced is fairly obvious, because they do require a lot of skill and experience. The "intermediate" label can mean almost anything.
I've played "intermediate" pieces that seem like baby pieces. I've played "intermediate" pieces that were insanely complex and yet labeled intermediate.
My recommendation: find a piece you REALLY want to learn, and then you should play it a lot until you master it. Simple. Through doing so you will either quickly learn a piece you love or expand skills over time learning a piece you enjoy to play. Either way you have a piece you enjoy, but the difficult ones will expand your abilities and provide you with heightened accomplishment.
There are probably no pieces in modern movie-pop that are written on truly advanced levels, and most are rather simple or basic. The difficult ones require speed or strong rhythm.
What's the best way to make progress on a song that I'm having trouble with?
Usually incorporating 4-Finger Chords with a bass melody. It's too much for my brain to handle at once. It also sounds wrong, not sure if being digital effects the chords.
I know I'm a little all over the place and I apologize!
The digital sound only becomes a problem when it is too far from sound of the original you are studying.
Change the voice of the digital piano/keyboard to be more like the original song, so you can mimic the piece better in your ears.
Just keep working the 4-finger chords. That's a basic technique you have to learn by applying yourself to.
Another problem is:
My current book has be going higher/lower than my 64 key keyboard allows me to go. Is there sheet music made for 64key?
I've never seen sheet music advertised or labeled as "FOR 64-KEY INSTRUMENTS!"
So I think you will have to contemplate getting a 72 or 88. I had a 72 (or was it 76?) key midi Yamaha cheapie, and I quickly switched it out for an 88-key Yamaha digital cheapie piano which I still use. There weren't many pieces which went so high, but because of 1 in 10, I made the choice and opened the wallet. You should think about buying up or dropping specific pieces.
Good luck with your studies!