linguistic deviation, idiolect, SLA, NS model of language, error, mistake, prescriptive vs descriptive use of a language.
once again, Meo: everyone makes mistakes. global errors, on the other hand, are repeated mistakes in your language that make you look like a fool, and need corrected. do you understand? if you do it once, it's a mistake. if you do it over and over, it's an error.
maybe you expect people in this snake pit to correct your errors with gentle guidance. it's unrealistic; most people here, including me, are going to make fun of you. either way, it's the same intent: we want you to stop using the language so awkwardly, and internalize the correction.
I try not to be a prescriptive grammarian, because I think that people who have to lean on centuries-old constructions are not only unintelligent, but also are denying the vitality of the language.
linguistic deviation is fine, and even constructive, if it makes sense, and gets the correct meaning across. you often don't. that you try to pass off your errors as creative use of non standard English is offensive. your confusion of "at first" and "first of all" is a prime example.
one last point: pairing fancy words with archaic constructions does't make people think you know the language any better. I see this mistake all the time with my students. they think that, when they could simply say, "using a thesaurus," if they say, "prevail upon the indubitable services of a thesaurus," it makes them sound smarter. it doesn't. it makes them sound ridiculous.