Switching to Shopify: Do I keep SiteGround and how to prevent premature launch?

[BigSal]

I am switching from an active woo commerce website to Shopify. I have transferred my products over to Shopify store and it is 75% designed.

Question One:My site is hosted by SiteGround and is up for renewal Jan 3. Newbie question but is Shopify my new hosting platform or do I continue with SiteGround and direct the DNS to Shopify?

Questions Two:  I don't want my Shopify store to go public when I redirect  if I am not ready yet so do I just keep it password protected until I am ready to launch it? Sorry - that was 2 questions.

Thank you so much for your help. 

[BigSal]

Thank you very much.

[BigSal]

So when I re-direct, Shopify becomes my Host?

[BigSal]

Thank you. I already have a customized theme but will keep you in mind. I just need to understand everything before I launch it:O) So if I keep the password on my store it will not be public - correct? I live in fear that it will launch before I am ready. I have been hesitating to redirect  the DNS because I was afraid that would make it live:O) Crazy Newbie fear!!! I appreciate your help.