oh, ok. but no matter mina or minna, 皆will still be their kanji right?
Yup. But you'll probably see "minna" in hiragana more often, I believe.
I don't have as much experience in Japanese, I was just going by what both my dictionaries say about 皆 [全部。すべて。] My other one says 全部の人 instead of just 全部. Wouldn't that pretty much include the speaker?
Go back and read what I wrote again. I said "mina-SAN" wouldn't work if the speaker is included. That's why one of my examples is "warera minna."
Minna is a great word. You can even say "zasshi wa minna urimashita" for "they sold all the magazines."
Also a little Marxist, but if everyone tries hard (in a togetherness sense), wouldn't that be uniting in a way allowing the second phrase of "We" to make sense?
Not necessarily. It's too ambiguous. It could be "if YOU ALL work hard, WE can have a good time." Very anti-Marxist idea, that -- but pretty much the way the PRC and the Soviet governments actually work.