You've turned user scaling off. Remove user-scalable=0
and you should solve that particular problem.
You should also get rid of the maximum-scale
setting unless you have a reason for not liking the default, which is 5.
"User-scalable: Determines whether or not the user can zoom in and out—whether or not the user can change the scale of the viewport. Set to yes to allow scaling and no to disallow scaling.
The default is yes.
Setting user-scalable to no also prevents a webpage from scrolling when entering text in an input field.
Available in iOS 1.0 and later."
(Note: 1 and 0 are sometimes used in place of true/false and yes/no. Here, your 0 is the same as no.)