Help With English In Reviews

There is about 50 reviews each day, so it would be hard, but when we reduce these in a good shape (after all, most of reviews written here are in a good English form, or at least it seems like it to me).

I'm not English Language teacher, but I'm studying university to be one. Even I passed all my English exams (and had problems with Czech linguistics, damn it), I know that I have certain problems with English, mostly when:

1)I'm not sure which preposition should be put there.

2)I'm trying to do some complicated compound sentence, mostly including my favorite element - would.

3)Am using both British and American English. Favorite / Favourite, but it can be worse

4)Am using it's / don't ... or even worse, terms like: wanna / lotta / gotta / gonna etc

5)Am not so sure how to say something and dictionary isn't helping, in these cases, results are terrible

6) (!) am doing grammatical mistakes. Mostly in tenses. Because yes, I want to be a teacher

7)Still am not able to tell where to put: a / an / the

8)Bad, Yoda-like order of words in sentences. Not bad, but may look like archaism.

Yes, I'm supplementing most of these by memory. I simply know that "this" should be written "here", from countless films, TV series, words I've read on the internet and music I've been listening.

Phrases, these are most easily to remember, as they are simply used.

Also, spell checker helps.

However, I can say basically everything I want to say. When I lack terminology, I search the internet for clue, guide, or hint, mostly on wikipedia (for rough information it's good enough)