Hi,
I have been in web and mobile development for last 5 years. I use Sencha Touch, Ext JS, HTML5, CSS3, PHP, J2EE, Salesforce platform etc for my development works. From your description I understand that you need an application which should work on both PC and mobile so I think that can be done very well using Ext JS which can be integrated into Salesforce platform easily. These functionality like different access levels for different types of users, CRUD operations, import/export of records and email sending features can also be implemented in a device independent way. Please elt me know if you are interested in working with me or if you have any question.
Thanks,
Ayan Dasgupta.