1 & 2 would require building custom JS. There are some topics here on validating date fields, however, most of the conversations pertain to the old ACF JS API. ACF 5.7 has a completely rebuild JS API https://www.advancedcustomfields.com/resources/javascript-api/. ACF also uses the jquery date picker fields. Most of what you’ll need to do will mean adding actions to the date picker fields. Sorry I can’t be of more help on this one, but there really is not a lot of resources I can point you. Everything I’m finding is for the old JS version.
