Also not a native speaker but もいいですか is indeed asking for permission as in "may I" do something.

I can recommend Genki and A guide to Japanese Grammar by Tae Kim. Honestly though, if you are a beginner, almost any textbook will do the job. 

Souvenir for Myself

Various things were sold besides food. I found very cute pictures of rabbit's and bought one of them for myself for the first time. That picture cost 30 dollars for one, but if I buy 2 pictures, it would cost 50 dollars. Therefore, my sister and I bought one each. When shopping with cards, I am used to finding a machine that reads credit cards almost anywhere. But this time, it was different. As I bought a picture from an individual, not a store, he didn't have such a machine. He connected a card reader to his smartphone and then I paid with my credit card. The receipt reached  my smartphone by e-mail. Wow! I was impressed with this method. I asked him ”Did you draw these pictures?" He said that his wife drew all the pictures. I really like them.

They were selling other stylish accessories and tableware and I wanted to buy much more, but I decided to end the shopping here with this.

Why alcohol overconsumption is worse than food overconsumption

It is because alcohol overconsumption is more likely to have bad effects on body.
Although moderate alcohol intake can be good for your health, excessive alcohol intake will increase the risk of alcohol related liver disease.
On the other hand, food overconsumption doesn't have as many negative effects.
Also, people sometimes drink heavily and cannot even make it home!
This can be another reason why alcohol overconsumption is worse.

TV program

I am a fan of the Leicester Foxes football club of the English Premier league.
A week ago, I heard the sad news of the Leicester owners fatal accident on the internet news.
It made me sad.
This morning I watched an English tv programme dedicated to his memory.
It had no Japanese translation so I couldn't understand everything.
I want to try to watch it again.

Could you please check my writing? Thank you.

Nice job!

About diet

I'm very particular about what I eat.
I try to eat food that is as healthy as possible.
I haven't eat rice for many years.
Sushi is an exception.But other than that I don't eat rice.
 I hardly eat bread or pasta, so I hardly ever eat carbohydrates.

Instead, I eat soy, for example bread and rice made from soybeans.
Soybeans can be used for various things.
They are not only healthy but also tasty.

About cooking,
I prefer to use organic vegetables.
I use them as much as possible.
 I don't use sugar.
People may think my diet is difficult but this is not true.

I eat meat and fish and cheese as much as I want.
I also eat a lot of vegetables.
So I don't feel stressed.
I like my eating habits.