Paul most of the jazz style tunes I play are from jazz transcriptions/special arrangements. When it comes to playing by ear that's a weak point for me so I never learn solo piano by ear. So far as advice the only thing I can say is continue to spend as much time you can practicing but you know that already.

I'll give you the run down how I was taught years back when I was working with a piano teacher. He had me working out of the Hanon series books for technique, also Czerny for technique as I advanced. Each week he'd assign technique exercise(s), a pop tune, a classical work, later when I wanted to take a crack at improvising he had me study chords. I could spend weeks on more difficult tunes so it wasn't necessarily a new tune every week. When it came to jazz he'd recommend a book of jazz transcriptions then I'd take and learn them note by note.

Today I don't spend any time with classical type music but when I can I take the Hanon book and play 10 or so of the basic finger excercises to keep my strength up in the weaker fingers. Hope that helps you!

As a side note, I learned "I Remember Clifford " in the early 90s and hadn't played it in years then Chas posted a version of it and I thought I gotta play that again. When I played it thru the first time I found it needed work so for about a week I spent about an hour a day working on it to get out the rought spots.