Oishisou, not oishii mitai. Mitai means more "similar to" than "looks like", so it doesn't make much sense. You can turn any "i" adjective into a word meaning "looks <adjective> by dropping the last "i" and substituting "sou" (EXCEPT kawaii, because kawaisou means pitiable, pathetic) and any "na" adjective by just adding "sou" to the adjective itself.
Jealous has a LOT of words. Envy, or light jealousy, is urayamashii. One of my favorites is yakimochi, which is the word for a cooked rice cake as well.
I'm surprised your dictionary has none...I find quite a few in several dictionaries, including the one in the learning center here on JapanesePod101 (staff members, take note: I want credit for this sale!
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Irritated/to be irritated is iradatsu, but there's many other words, depending on what you mean by it. A sentence would be easier to try to translate than a single word.
Sean