To be an optimist you would need to be very hopeful about an occurrence, or the whole existence of the future. You would need to be very confident that the future will be successful. The opposite of being a optimist is a pessimist.
No, the word optimistic is an adjective, a word that describes a noun, for example an optimistic attitude. The noun form is optimist, a singular, common, abstract noun. Example sentence: An optimist sees the glass as half full.
In modern English I wish I were an optimist is correct. Remember that was is the past tense. That sentence is talking about something that the subject is not, so it means: "I am not an optimist, but I wish I were."
Optimist is derived from the Latin optimum meaning "best thing". An optimist is a person who tends to have a positive view on most things. People who are optimists generally expect the best outcome in a situation.
An optimist is one who "sees the good side" of things. For any given situation, an optimist generally finds a reason to be hopeful for the future. The opposite is a "pessimist", who is always finding reasons to be sad and discouraged.