I have a book similar to this one:
Amazon.com: Piano Chord Dictionary (Handy Guide): M. Manus: Books
LDB For Chord progression I would just get the chord book above or something similar to it. Then learn about the circle of 5ths.
https://www.illmuzik.com/forums/showthread.php?t=20049
dont forget about my thread now.
All I know about chord progression is moving my fingers into three finger combinations until I find what sounds right. Some times the progression will be just moving one finger up or down a half note.
I have heard a rumour somewhere along the grapevine that chords have a reverse chord too, but with out pics its pretty hard to explain. I dont really know much about chord theory, just what sounds right.
http://www.dolmetsch.com/index.htm
Fantastic online resource. Learn some basic music theory, known your scales and modes, practice your fingering and your music skill and the quality of your beats will increase ten-fold. Not only will you be able to mix original music with samples, you will eventually be making beats from scratch without samples - getting to the point where using a sample is a choice, not a necessity.
Also, even if you only understand the basics, you can communicate with musicians i.e. keyboardists and guitarists - learning how to play is the step from beat-maker to producer.