How long does it take admin to reply on my ask?

1-3 days, depending upon your question ^^ (and as long as tumblr doesn't mess up anything especially in mobile version)

Off-Anon asks?

Shrine Admin will usually reply in private unless the content contains something of vital info regarding the ship, Suho, Kai or EXO. In that case, admin will publicly post your ask (unless you ask not to. Shrine Admin shall respect your privacy).

I want to contact the admin but tumblr keeps on screwing up ;-;

If you have twitter, you can use that. Just mention @duojeikei so that Admin can contact you too.