For your purposes, I would suggest starting by learning a couple of chords. I would suggest G, C and D. If you just learn those three chords, which should take no more than a couple of days if you focus at it, you'll be able to play thousands of songs and have a good time while you extend your skill set.

As for instruments, my choice would be to find a middle-grade second hand guitar to start on. If your fingers are soft or delicate, it is true that nylon strings are easier to play on. Get someone familiar with guitars to check out the accuracy of the fretting, if possible, and the trueness of the harmonics at the 5th, 7th and 12th frets. Once you get used to singing and playing a bit you can decide if you want to invest seriosu money in an instrument or not. If you find that you have the yen to perform for others you'll want something better, perhaps, but you don't need to figger on that now.

A