If you really are a 'high level pianist' and have an 'extensive' background in music theory, the guitar will seem quite EASY to you. That's what it was for me. What I mean is that you think it's more difficult than it really is (for a classical pianist). I started as an electric guitarist, then after years I started practicing classical piano and completely neglected the guitar. When I returned to guitar, I made huge leaps easily, in a very short time. In less than 3 years I had mastered BOTH electric guitar in my chosen styles, as well as classical guitar. However, let's remember that I did NOT start on guitar as a beginner guitarist, so in your case it will take longer.
The guitar seems hard to you now, principally because the fretboard, as oppose as the piano's keyboard , is counterintuitive.
Obviously, it won't be TOO easy, but certainly easy enough, if you know exactly what to do and how to do it. Obviously it is impossible to explain these things here; it would be like trying to describe how to master tae kwon do by writing a couple of paragraphs about it.
As for your question about improvisation (if it's 'noodling', it's mediocre improvisation, in my opinion just a waste of time), look no further than Frank Gambale's book called 'Improvisation Made Easier'. It's not an 'easy' book but it's easy enough.
Why do I say it's easy for a classical pianist, to be a modern guitarist? Here's an example: an high level pianist can learn to play Bach fugues at the piano. An high level modern guitarist, can, say, improvise good solos over a backing track. Or writing songs and pieces. All good stuff, but learning to play Bach fugues at the piano is another level entirely. If learning to play like George Benson is difficult, then learning to play Bach fugues at the piano is insane. This is also true of piano music such as that by Chopin or Liszt, as you know.
What I am really saying is: you seem to be a bit intimidated by the guitar, but I assure you that there's no reasons to. If you follow a good and effective method you should be able to master it in less than 2 years. And I mean master it. Obviously I can't explain the process here in a page, and if anyone can, then that's no method. In general, my advice would be asking: 'did you teach yourself classical piano?' The probably answer is 'no'. Then I would say: 'Then don't teach yourself the guitar either'. The moral of the story is that too many people are confident that they can 'teach themselves', but even in the best of cases, it's going to take 7 times longer. Some geniuses of the guitar, like Joe Pass or Allan Holdsworth, taught themselves. But for the rest of us, who are no geniuses, teaching oneself is a waste of time, even in the best of cases. In other words, find some good teachers and learn the thing fast. It's really simple. That's what I would do. No reason wasting time, life is short, and we all get older far faster than we will notice. Good luck.