I am planning on the creation of a mobile application to keep track of 100+ collectors items, users will check on their application the item number they get, so it will keep track of the items still missing, I have three questions that i am still deciding on user data storage, any feedback is greatly appreciated.

1- local storage of data or web storage of data is chosen
2- what will be the best option to save the data locally or web
3- does the html5 feature "web storage key/value pair" will be and option and can be use for mobile application?

I am planning on using Phonegap as a frameworks and create the application using HTML5, jscript and css.