#1. I do not speak Swahili so I couldn't answer that. I'm not even sure you can compare these two languages. And I am sensing that you may be talking about another type of "creole" (other than Haitian Creole?). Are you planning a trip to St Lucia, Haiti, Martinique, or ...Seychelles? There are some differences in the creole spoken in these places and others.
#2. That I know of, English, Spanish, French, and Italian speakers pick up the Haitian Creole language really quickly. You bat your eyes and they're already speaking like natives :) I do not know about other nationalities because I haven't come in contact with them. But I'm sure they would learn quickly as well. I imagine the effort you put into learning a language would dictate how long it takes for you to learn it. But even after you've become fluent in a language, you will be a student of that language for a lifetime. I am a lifetime student of H. Creole, French, and English; and an active student of the Spanish language.
#3. Depending on which creole you want to learn, start looking online for classes offered at colleges, universities, community centers, churches, etc.... You should be able to find Haitian Creole classes you can attend in person in places with high population of Haitians (Florida, New York, Mass., Pennsylvania, the Carolinas, New Jersey, Conn.... Haiti, Canada, France.... there are many locations!) And if you can't find a class in your neighborhood, you can have a similar experience with online classes offered via Skype. Just start your search online and find the right class for you.
Bòn chans!
Haitian Creole ↔ English Reference, Look up Haitian Creole and English Words
Just in general I think you could say:
Jezi fè sa (Jesus does that/this)