Laws of the First Blessing - Of "Who Forms" - and in it are 5 Se-ifim [The blessing of] "Blessed are you Hashem our Lord who forms light and creates darkness" was established to mention the attribute of darkness during the day to address the claim of heretics who say that "The one who created light did not create darkness."
If one erred [while praying] and said "the one whose word brings forth evening" but remembered immediately and said "who forms light," and then ends with "who fashions the luminaries," he has fulfilled his obligation. However, if one said "the one whose word brings forth evening" and one did not say "who forms light" or did not conclude with "who fashions the luminaries," then he has not fulfilled his obligation. And if one said, "the one who forms light and creates darkness and whose word brings forth evening," and also concluded with "brings forth evening," he has not fulfilled his obligation. Rem"a: And the same thing applies if one only said at first "who forms light", if he ends with "brings forth evening" then he has not fulfilled one's obligation (his own words to explain the Tur and the Rosh). However, if one concludes with "who fashions the luminaries", since he opened with "who forms light", he has fulfilled his obligation even though he interrupted with "brings forth evening."
There are those who say that the Kedusha [text] in [the] Yotzer [blessing] may be recited by an individual [who is praying alone], since it is only a recitation of a [Biblical] narrative. And there are those who say that an individual [praying alone] should skip over this part, and it should only be recited in public. And one should be concerned for their words (ie. of the latter opinion) and make sure that [if] an individual recites it, he does so with a melody and cantillation, as if reading a Torah portion. Rem"a: And the custom has already become widespread, [that we follow] like the first opinion, that an individual recites it. And when they (ie. the congregation) answer this Kedusha, they say it aloud (Hagahot Maimoni in the Formula of Prayer).
The blessings for Yotzer (morning) and Aravit (Maariv Aravim in the evening) should be said alongside the prayer leader at a pleasant pace. Rem"a: And one should hasten to conclude before the prayer leader concludes in order to answer Amen after the prayer leader (Hagahot Maimoni Chapter 1 from Laws of Blessings and Rokeach Siman 218). Nevertheless, if one did not say it [himself] but heard it from the prayer-leader then one has fulfilled one's obligation, because [with regard to these blessings] the prayer leader can fulfill the obligation of an individual, even if one is an expert (ie. he is fluent in the prayers). Nonetheless, the prayer leader may not fulfill the obligation of an individual with less than a minyan (Rabbi Yitzchak on Mi Shemeyto). However, one should not answer Amen after the blessing "...who chooses His nation, Israel, with love" because this constitutes an interruption (see below, chapter 61)
If one made an error in [leading] the Yotzer blessing in a way that someone else has to replace him, if the error came after the Kedusha, the replacement leader does not need to return to the beginning, rather he can continue from the place where [the original prayer-leader] stopped. Rem"a: That is, one continues from after the Kedusha and on, but if the mistake comes before the Kedusha, one needs to start from the beginning [of the blessing of Yotzer Ohr] (the Ri and the Rosh in "Ein Om'din", Hagahot Maimoni Ch. 10 of Laws of Prayer, and Tur).