Actually, the domains tend to have different IP addresses, but they are not unique and are in fact shared - just with other people rather than other domains you are hosting. You would need to purchase the unique IP address feature for $3.95 a month or use a promo code that offers a free unique IP address.
An SSL certificate is not offered as part of any promotional package. You don't have to have the Business plan, you just have to get a unique IP address and buy your own cert. If you look around, you might be able to find one for as little as $20 a year. Though I'm no expert on certs, that seems an unbelievably low price.
The way the free domains work is that your account gets marked every year for N free domain registrations. As you renew or add a domain, you use them up. When I signed up for DreamHost, I didn't even register my first domain because I transferred a domain in. When I registered a domain it used up my one free domain registration. I will be able to renew it every year for free.
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