a) Make clear available: I think you shouldn't set it to required. Instead you could write something like this:
$('#fromDate').on('change', function(){ if(!$.prop(this, 'value'){ $('#untilDate').prop('value', ''); } });
Does this help?
b) clear locale Yeah, I know. I was very lazy here. It would be extreme nice, if you could compare english and swedish locale for me and do a PR with improved and more usable errormessages/locale settings
Yes. There is the "startValue" option. See in action (afarkas.github.io/webshim/demos/demos/cfgs/input-date.html#startValue=2012-12-12&startView=2):
input type="date" data-date='{"startValue": "2010-12-12"}' /
a) Currently not. My mobile strategy is to leave input widgets native on mobile and only set replaceUI on desktop.
b) required not working on iOS. Which iOS version are you using? I'm not aware, but if it's iOS 5.1.1+, I will look into it.