Some sentences

Excellent sentences! Here are my very small corrections:

#1 - (Zip-up) Hoodie
This store sells a variety of (zip-up) hoodies. So I don't know which one I will select. Excellent job! We do not have a separate word for zip-up hoodies, so the phrase you want to use is simply "zip-up hoodies".

#2 - One-piece Dress
My girlfriend wears a one-piece dress often when she meets me. When we talk about dresses, the default is one-piece so you do not have to specify. If she were wearing a two piece dress, we would call that a skirt and blouse (shirt). 

#3 - Sweet suit
I didn't know the word sweat suit until now. I've used the word training uniform instead of sweat suit. Excellent grammar! Small spelling error.

#4 - Trench coat
Many korean people tend to call a trench coat burbery. Great job! You were only missing an article for "trench coat". 

#5 - Dress shirt
My company allows employees to wear business casual attire every Friday. The word "Friday" should be capitailzed.
However, I nearly always wear a dress shirt with a suit because I don't know how to wear business casual attire well. 
So I'm a little jealous of people who wear it well in a good way (nicely). Using the word "jealous" in a nice way is a little difficult in English. It has a lot to do with tone of voice and facial expressions, but when you're writing you cannot rely on those. So the best thing to do in this situation is to qualify it with the phrase "a little" so that it is clear that it is not severe jealousy.