One of my first books was the picture chord encyclopedia. It has photos and diagrams for over 2,600 different chords. Well actually each chord it shows is in 4 different voicings. But anyhow almost every chord you could imagine is in here. It is published by Hal Leonard. You may also want to check out books in a reputable book store and many, many music shops. There is literature everywhere out there.

As far as being out of tune, let me be the first to suggest a chromatic tuner you can buy these very cheap, I think around 12 bucks or so. Considering that it is for an acoustic make sure that it has a built in mic. Learning an instrument out of tune is about as comparable to learning to drive a car with your hands tide and blind folded. It jut wont work.

And picks are not nececarily a must. If I am strumming chords I dont use one. I know there alot of people out there that frown on this. But I look at it as "my music-my rules". Music is every bit as personal as the person who writes it. Dont let anyone make the rules for you, if it works for you go for it.
Well thats my opinion. didn't mean to get long winded.