Are these OK?

1.

Did you get the Visa yet?
Henüz Vizen var mı?

2.

Maybe he will get angry at him.
O belki ona kızgın olacak.

3.

It was so cold that the schools had to close.
O kadar soğuktu ki okullar kapanmalıydı.

Did you get the Visa yet?

I would say ´Zaten vizen var mı?´ 

And maybe "Belki ona kızgın olacak." without the "o".

Nope

Thankyou.

Maybe he will get angry at him.
O belki ona kızgın olacak.

Belki ona kızar. Does that mean in the near future?

I mean like someone gets mad often. So I wonder, maybe someday, he will get mad at another person. Is O belki ona kızgın olacak grammatically wrong?

...OK, I looked it up, Aorist:

(3) Uncertain Future

The Simple Present is also used for future events which are not timed.

Makes sense. So is kızacak also OK here?

Right, I know what you mean now, very eleborate. Thank you for this elegant contribution to my knowledge of the Turkish language G.

And it´s ´yet´ as in ´already´, whereas ´hala´ means ´still´. 

Hope it´s helpfull.