Shalom,
1.א Does the prohibition of forgetting torah (T"T 1:10) that anytime one is not learning, one is forgetting?

ב a source for a constant chiyuv of talmud torah?

ג Likewise, the Rambam quotes in Sefer HaMitzvot the limud that torah be fluent in one mouth, is that a source for constant chiyuv?
2.א. Is the mitzvah of dividing into 1/3 talmud torah a din deoraysa.

ב If so, how can one fulfill T"T daily by just saying krias shema?