Are correct?
I used to swim twice a week when I had 12.

I (didn´t or not?) used to smoke so much, but now yes.

I´d visit my grandmother on (a?) Tuesday morning when I arrived to my village.

I´m used to going to the swimming-pool after lunch in (the?) summer.

He (doesn´t / isn´t?) used to eating with chopsticks.

I´m getting used to the hot climate.

He couldn´t get used to playing the guitar with his eyes closed.

Question

Are correct?
I used to swim twice a week when I had 12.

I (didn´t or not?) used to smoke so much, but now yes.

I´d visit my grandmother on (a?) Tuesday morning when I arrived to my village.

I´m used to going to the swimming-pool after lunch in (the?) summer.

He (doesn´t / isn´t?) used to eating with chopsticks.

I´m getting used to the hot climate.

He couldn´t get used to playing the guitar with his eyes closed.

Answer

... when I was 12.
... but now I do. 
... on a Tuesday morning (this whole sentence could be different depending on the context.  Are you writing about what you are planning to do,  or about what you did in the past?) 
... the summer 
... isn't
Correct
Correct

Answer

Please write on note instead of Q and A if you want have your writing corrected.

Answer

I used to swim twice a week when i was 12.

I didn't use to smoke much, but now i do.

I'd visit my grandmother on a Tuesday morning when I arrived in my village.

I am used to going to the swimming pool after lunch in the summer.

He isn't used to eating with chopsticks.

I'm getting used to the hot climate

He couldn't get play the guitar with his eyes closed.

Well done your English is very good.