I need an app developed API Hooks in and Out

General information for the business: Sales of product
Kind of development: New program from scratch
Description of every module: IOS and Android Application development
Lead Capture ( customer sign up and integration with remote MS Dynamics installation)
API integration with 3rd party for content: Stock Control and Centralised Marketing Collateral Control
Product Catalogue with Stock Maintenance: Ability to display PDF and content from web
Email Send: Ability to create and send promotional email containing promotional content (attachment and formatted HTML)
Offline ability to display and function until internet connection available.
Description of requirements/functionality: This is a b2c application and sales tool. Focusing on tablet/ipad use. User login and usability paramount.
Preparation of email containing marketing collateral
User login
Customer Sign up and enquiry generation (Check against database for previous connection)
CMS and Admin requirements: Reporting needed on application use, logins, sign ups, email creations, off-line use data capture. Reporting available under master login.
Specific technologies required: IOS, ANDROID, API (REST), MICROSOFT DYNAMICS, INTEGRATION
Extra notes: Must be built with ability to be white labelled and added to a different project / sales team. Multiple use and easily updated.

Questions:-

Please provide examples, case studies or testimonials relevant to this line of work. Do you have experience in this line of work?
How would you build the product, what about IOS / Android updates, how would you ensure the application remains functional?
Will you build in HTML5 or C#?
Have you worked with integrations such as app / HTML5 / Wordpress to MS DYNAMICS before (may extend to another project)