New Macbook pro battery problem

I just bought the new Macbook pro 13, but I found a fews problem of my mbp.

First, the battery battery draining fast. I just open excel, google chrome, and sometimes Spotify. But the battery only last for 4-5hours?

I never used a mac before. So, Is it a problem or just normal?

Second, I found the battery percentage is not correct! It will stop at a number and not change, and suddenly change to a huge different no.

For example, 2:30-4:00pm the battery shown still at 21%, and then 4pm suddenly change to 7%. between the 2 hours didn't show any other no. to let me know the real percentage.

And I found out if I really want to know the exactly % or how many times left until battery charging is full ,

I have to click the icon, and choose Show Percentage. then it will finally updated the times / %.

Do I need to return my computer? or is it just a error of the system?

Sorry for my bad english. Hope you understand what am I talking about.