Yes, he does use askfm and it is HarryEdwardStylesHazza.
You can get more followers on askfm by following more people, answering all questions you are asked, invite friends. For more information check out askfmtrackerapp.com/how-to-get-more-followers-on-ask-fm/
You will need to make an account on askfm to ask a questions. After your account is made, you will be able to ask any question.
Probably but, the block people that they don't know.
how u know the block is really cracked
We can't be sure. There are a lot of posers. The only way to know is to ask Leighton herself. I wouldn't believe if she hasn't confirmed it.