In a way, yes. The term "flashcard" traditionally refers to the form in which you can keep information in order to support memorization process.
While Memjogger uses the notion of flashcards for storing your knowledge, it also implements algorithms that are responsible for performing repeats of specific cards at the optimum moment.
Currently Memjogger implements one spaced repetition algorithm which is based on the SM-2 Algorithm, © Copyright SuperMemo World, 1991. www.supermemo.com, www.supermemo.eu.
Yes. It's full documentation is available here.
Not yet, but stay tuned!
Although every information you put into Memjogger is held on the server, the service comes with the export function that, at any given moment, allows you to save all your data to your own computer.
That means that your flashcards always stay with you. If, for example, at one point you decide not to use Memjogger anymore, you can just export them and use later in any way you want.
See detailed description on how to save flashcards to your own computer and what export formats are available.