To rule on a law

1. If someone who has not reached the teaching level, has not completed Shas and is not familiar with the poskim, etc., studies a certain issue, and sees that the conclusion of the halakhah contains a disagreement among the latter, and from his study of the issue it seems to him to be one of them, can he act according to this method? Or, since he has not reached the teaching level, is the matter not beyond doubt, and he must act according to the rule that doubts in the Torah are to be stricter and doubts in the rabbis are to be lenient?
 
2. What (in your opinion, that there is almost complete autonomy and that everyone should learn and arrive at a halacha from the study according to their understanding) is the meaning of the rules of the paragraph? What does the rule of “halacha as a rabbinic text, halacha as a tradi, halacha as a mere mishnah, halacha as the Rambam or the Riff, halacha as a mara da’tra, etc. etc.” mean to me if in the end I have to reach my own conclusion?