1. You get priority boarding and tendering with suites and access to the priority line at guest services. You also get to pay more in gratuity despite them not doing anything at all extra.
You can keep the adjoining room doors open all cruise if you wish and make your own suite.
2. Anything is possible. Heaven forbid a storm hits Grand Bahama and delays construction, your cruise is re-routed to Nassau instead, and you paid more for that cruise for nothing. It's also possible, and perhaps more likely, that you'll be one of the first to enjoy Carnival's newest proprietary port of call if you book that cruise. So it's really up to you. I was among the first at Amber Cove on Ecstasy back in the day.