I've been thinking about your tangling, knotting problem. My first choice with frogged yarn is to wind it around the ball it's attached to but if that's not a great option and even though it means more ends to weave in eventually, if I have to frog enough yarn to be a knotty problem I'll cut and wind it up. I've made loops of the yarn and hung it on something too but that still can end up in knots and tangles.
Have you managed to finish anything? Something simple, small, and done is a great morale booster.
I should never overestimate my basic arithmetic skills.