Moving site from one domain to another

I may have to move one of my websites from one domain name to another (which I also own). It’d be staying with the same hosting company; in fact, both domains reside in the same account with that hosting company.

1. How do I move the site?
2. How do I redirect traffic from the old URL (which I’ll continue to own) to the new one?
3. The original domain has some killer SEO. Obviously, the internal factors (text, keywords) will transfer over. But is there a way I can ensure the link juice from inbound links now flows through to the new site?

Thanks for any help you can provide!