Karma, karma, karma, karma, karma kaméleon
Jössz és mész, jössz és mész
No, "Come and go!" is imperative in English - you're telling someone what to do. You would use different endings for that in Hungarian. You could omit the pronoun the second time, though: "You come and go" would be good.
(There is a sort-of imperative usage of the ordinary second person present tense, but it's something I've only heard used with dogs and small children. Leülsz! is not exactly "Sit down!" but it can be used as a not-at-all polite command more like "You WILL sit down!".)
"Azonnal leülsz! Megértetted??" - You (will) sit down immediately! Did you understand?
I guess these not-so-polite commands tend to use verbs with preverbs. Makes sense, the emphasis is on what the result of the action should be. "I want you to be in a sitting position immediately".
Dog-Hungarian may not follow this guideline though...
Nope. In German we would rather just say "Sitz!" to a dog. Way shorter. Imagine repeating that long sentence over and over to a dog that doesn't listen. ;)