It probably has to do with the phonetic and metrical properties of "ladies and gentlemen" versus "gentlemen and ladies." Say them both out loud and see which one sounds better to you, intuitively.
Ladies and gentlemen everyone [nothing] friends / folks / team Avoid mixing and matching: both hey there, ladies and gentlemen, let's rock! and S'up, honoured guests? are kind of weird. Not impossible to use, but definitely an expert technique. It's fine to say Good morning folks though.
Dear ladies and gentlemen, having made sure to include the names of all the recipients in the postal address block pertaining to the addressees (if you are sending everyone a paper copy of the letter), so that all of them are able to see who else is covered by your salutation.
The plural possessive is "ladies'." "Lady" is singular, so if you were referring solely to one woman's shoes, it would be "the lady's shoes." As for your second question, I'm assuming you're referring to a group of women in your salutation of them, so it would be "Good morning, ladies." And as you're addressing them directly, the comma preceding "ladies" is necessary.
Hence, there is no ambiguity with the men, and for the same reason no ambiguity with the ladies. Ladies is the plural form of lady, so the apostrophe goes to the right - ladies'. If you are wondering why we don't write ladies's, it is because ladies is one of the exceptions, along with girls', parents', players', weeks' and even Klingons'
Ladies Captain means the Captain responsible for Ladies Golf elected to represent the Lady Members at Club and County level and to fulfil [sic] any requirements of the relevant Golf Association.