RE: the crochet thing. I had that problem when I wasn't making the right number of chains at the end of a row. Also, is it possible that you are chaining tighter than you actually crochet?
RE: the knitting, can't help you too much with the first dilemna, but the second could be that you are not bringing the yarn behind the needle when you turn your work. It should wrap around counter clockwise, or else you will end up with 2 stitched where there should be just the 1.