What parts of Torah fit into the definition of כל התורה קולה? What exactly would one have to learn in order to complete it?
It is impossible to give an exact definition to what כל התורה כלוה is, a the posek says א”רוכה מ”ארץ מ”דה (see Yalkut Shimoni Shemos 273) that the torah is wider than the earth etc. The word of H-shem and His knowledge is endless. However what would generally be considered having a wide knowledge of torah would be knowing Tanach, Talmud Bavli, Yerushalmi, Tur , Shulchan Aruch, Poskim, and Zohar etc. Start with that, and you will see that it is really alot more to know. That is why the bigger the talmid chacham, the more they feel they have to learn.