Transfer Squarespace Domain & Email

I need a smooth, zero-downtime move of both my domain and its future email service from Squarespace over to the registrar and hosting environment at www.design.com.

Current setup
• Domain is registered through Squarespace
• No custom mailboxes yet—right now I use a general email service tied to the domain’s contact form
• The live site is a Squarespace blog with articles; content stays where it is for now, I’m only shifting the domain and setting up mail.

What I’m after
1. Unlock the domain, obtain the auth code, and complete the transfer to design.com.
2. Configure DNS so the site remains reachable throughout the transfer.
3. Once the domain sits at design.com, create and verify new email accounts on my chosen plan there, set MX, SPF, and DKIM records, and test delivery both ways.
4. Provide a short hand-off document so I can manage renewals and add mailboxes later.

I’ll supply any required logins right away, and I’m happy to schedule the cut-over during a low-traffic window you recommend.