Cmc and tylose both perform the same function as icing strengthners. Both are syntheically produced man-made and unlke gum trag which is non synthetic, more expensive and requires time to mature / fully activated in the fondant; you can use fondant mixed with cmc almost immediately. Hope you find this useful!
As for a gumpaste recipe, it really depends on your end product. Gumpaste recipes for flowers usually have crisco – vegetable shortening added, while those for modelling at times omit this. Try out the different recipes – online, till you get one that suits your demands.