The reflexive pronoun "myself" in Sentence 1 is an indirect object--in this case, the beneficiary of the action. It corresponds to the construction with the preposition "for." It's unstressed.
"Myself" in Sentence 2 can also be considered an indirect object, although "have some fun," unlike "find," doesn't normally take an indirect object. The reflexive pronoun "myself" in this expression gives the impression that the grammatical subject is both the beneficiary and the "instigator" of the same action.
Similar examples, from Google, include
--What an unsecured hand weapon was doing lying in a storeroom was another matter, one I would take up as soon as I had myself some more sleep, which wouldn't be today.
--I had myself some really good times but then I managed to catch the eye of the young Mr. Michael White of ˜White Cosmetics' fame.
--You just go on back to sleep now. And have good dreams. I had myself some good dreams in that very bed once upon a time.".
--Steve Francis (21.0-6.2-3.7) finally was able to put his migraine headache problem behind him and have himself a career type year.
--Andrzej wakes up when he hears a noise and goes up topside to have himself a look.
--I guess John will go have himself a longer vacation!
This use of the reflexive pronoun is colloquial, not formal, usage. Like a "true" indirect object as in Sentence 1, it's not stressed in speech.
In Sentences 3 a and b and 4 a and b the emphatic, non-object, reflexive pronoun "myself" does carry stress, to emphasize that the speaker, and no one else, performed (3) or is going to perform (4), the action.