How to get the best teacher reference for uni application...

Nothing at all about extra curricular activities in 2/3/4 - those are the paragraphs you devote to each subject. They should contain an assessment of your aptitude and attainment in the subject.
Paragraph 2: e.g. maths
Paragraph 3: e.g. physics
Paragraph 4: e.g. chemistry
Paragraph 5: dropped subject.

Extracurricular activities go in the general bit of Paragraph 1, and possibly also in paragraph 6 at the end.

Which paragraph should include my predicted grades and what kind of subjects should it predict to? All of my subjects or just those in the reference, required by the university?

Mine was written by someone who had never taught me nor did he teach the subject I was applying for.

I see you're applying as an individual. Well... To be honest, it is just my opinion. I just thought that requesting a reference this way would sound more convincing. It's up to you, really. The referee should know you well enough, academically speaking.

No, I'm not, and I got into 4 of my 5 unis without having what you think is needed...

Ok, I see. Everyone have their own ways of doing things.

Well but I just put mine out there because you seemed to say that if you don't, it's over. And that most certainly isn't true.