FROM SUPPORT FOR OTHERS TO LEARN FROM:
It will work because the name servers set for the domain do not control whether you can actually add things or not in the Dreamhost system. Will what you do here be visible to the public internet? No, it will not, until the name server change.
You can add secure hosting first. You need to be sure to use a "self-signed" certificate (do NOT order a professional one from the
Dreamhost panel). That turns on https for you. You later come back with the certificate from GoDaddy and install it, replacing the self-signed certificate with it and its bundle of intermediate certificate in the forms for them on the panel.
No. As noted above, nothing you do in the system here affects what visitors see on the internet until you change the name servers for the domain.
I'm sorry about that. The possible steps are on the wiki, actually: http://wiki.dreamhost.com/Secure_Hosting
The choice of self-signed vs ordering from Dreamhost or using another provider's certificate is provided on the panel when secure hosting is being added as well as later, when secure hosting is already active, but I can see that it might be confusing when seen initially (item C). Re-hosting is nothing more than moving a domain from another host to us; the distinction of whether it was hosted here previously doesn't matter unless there's still hosting setup for it here on a different hosting account), which is items A and B, so if you add hosting for a domain, a reminder about the name server change is briefly shown, but, again, that doesn't mean it can't be missed. Hopefully, I've clarified a bit. If not, let me know what's still fuzzy.
Thanks! Ryan C