You can switch the language in the upper right corner of the DLsite web page.
You can pay by credit card. ヾ(•ω•`)o
First you can go to the page to buy points:
https://www.dlsite.com/maniax/mypage/user/buy/point
Then select For Books (you will need to sign up for a For Books account).
Then select "More payment options" and use Card.