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'.

Understanding the Context

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' The metrical pattern of "ladies and gentlemen" consists of (arguably) two dactyls. A dactyl is a group of three syllables where the first is stressed and the second two are unstressed. 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. In some settings, "ladies" is still treated as more appropriate: A fine restaurant's host might ask "If you ladies and gentlemen would pease follow me?" I'd still instruct a kid, "Thank the nice lady, Bobby, for catching your ball before it rolled into the street." "Woman" often sounds more serious, and is preferred in no-nonsense settings.

Key Insights

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.

Final Thoughts

Both "Ladies' Beer" and "Ladies Beer" are acceptable, but there is a slightly different implication depending on which you use. "Ladies' Beer" is written in the possessive form, and thus implies ownership. Should "Ladies" be marked with an apostrophe in the noun phrase "Ladies ...