Drawing by hand can teach you so much about the logic of typefaces, but digital lets you experiment so much faster. Both approaches have so much to offer for learning. Personally I sketch ideas for letters all the time but as soon as one letter, or one word, looks good to me, I move into digitizing. I can use my one letter to build half a dozen others in minutes and get a better idea if the whole design might work as a font.
The question is what is the reseller doing for your sales that you wouldn't be able to do yourself. To paraphrase an adage from the book publishing world - making fonts is easy, selling fonts is hard. A 50/50 split is fair if the retailer is providing you a platform for higher sales. Not that I wouldn't want to be getting more
For self teaching, I would recommend the following books (for making type, not using it): 'Fonts and Logos' by Doyald Young, 'Designing Type' by Karen Cheng and 'On Stone' by Sumner Stone. The Young book is fantastic for pointing out small details, the Cheng book covers the basics and the Stone book covers a specific case in great detail.
my two cents on Calligraphy: practicing calligraphy helped me enormously to see why certain certain curves worked better than others and to learn the logic of certain letter forms, especially using a broad nibbed pen. Suddenly the long 's' made sense!