BobF
craigb
BobF
Don't bother thinking about lessons. I've been thinking about lessons for decades and it hasn't helped a bit 
OK, seriously. My primary is guitar but I've become interested more and more in getting better with keys. Are piano lessons the foundation for all things keys/synths?
No Bob. That would be tuba lessons.
(I keed! I keed! 
)
You funny guy, Joe.
I ask this because of the obvious differences I hear in approach to pure piano pieces and synths/keys that I hear as part of a rock ensemble, for example.
My question is really about style, I guess. Will playing Floyd Cramer or church tunes on piano help me play better synth parts for my own rock creations? I can see where basic fingering exercises to develop muscle memory would be a huge help. But style is a completely different aspect.
When I was a kid playing power chords on my guitar, my brother was taking piano lessons. He was pretty good, but his repertoire was entirely gospel. Something neither of us had any real interest in playing.
Ok, the real answer has two parts.
The first one is this: Find the right teacher. DON'T get an 80-year old lady as your teacher (which should remove the gospel parts). Find someone who can teach you all the fundamentals of playing keyboards. I know that, when I get this chance, I would like a little bit of Classical knowledge as well as some organ exposure - wait, that didn't sound right!
What I mean is that my goal will be to play MY own music, but I'd like to know the correct way to play a piano. I'd also like some exposure to how Classical music is put together and played (so I can incorporate aspects I like) as well as the basic fundamentals of how an organ is played (which builds on the piano parts and adds "boards or ranks," "drawbars" and "pedals" for example - proper organ playing can really sound good even in non-traditional songs).
The second part is: You will also want to learn how to create and synthesize sounds (analog and/or digital). This includes wave types (sine, saw, etc.), ADSR envelopes (attack, decay, sustain, release), portamento, latching, arpeggiation, wheel usage (volume & modulation), filters (resonance, cutoff), oscillators (like LFO's which are Low frequency oscillators), identifying common sounds & patches (pads, drones, strings, brass, vocoders, etc.), keyboard mapping (splitting, octave shifting, sampling, key transposing) and MIDI.
Because combining all of this is important to me, I would not buy a piano but would go for two items (which may be in one device, but I would prefer being separate). One is a decent, weighted keyboard (probably 60-key, the up & down octave buttons will help cover the rest and I wouldn't have to be limited or abusing those buttons as you do on shorter keyboards). This keyboard doesn't even have to be able to generate sounds, it could be what is called a "dead, MIDI keyboard." A useless device until it is attached to something that can use the MIDI notes generated. This second device would be a proper, high-end synthesizer (preferably with its own keyboard which can be shorter, say 49 keys). This gives me the best of both worlds. The feel of a nice piano with the quick tone generation of a synth. There are also MIDI-capable add-ons that can provide organ sounds, effects, bass pedals and drawbars. Plus, when you start to want even more tones and sound-creating abilities or effects, you can get additional rack units (i.e., no attached keyboard) and control them from your MIDI-capable keyboards.