I would strongly suggest a good used acoustic piano. Who cares if it's a little out of tune? The old upright sitting in the entry way of my house isn't perfectly in tune, but I can still teach scales to the grandkids, explain chord structure to the wife, etc. I've seen it 1000 times...aspiring musicians think if they go out and buy top of the line equipment it'll make it easier to learn this just isn't so in most cases.
I would stay away from keyboards until you have advanced a good ways. I say this because keyboards with their built-in transposers have a tendency to become crutches because those playing them can program them so that everything is in the key of "C". One of my good friends and musician buddies who learned to play by ear, in any key required, started playing a keyboard and transposes everything to C or F, wasting all that hard-earned learning.
As far as learning goes the suggestion I give people who want lessons from me is to buy a beginner's book and go through it. When you finish that get the next level up and continue until you hit a wall then find a teacher.
Good luck!