Digital menu IOS app development

I am interested in developing a digital menu app for iphone and ipad which can be administered using a web based system. I don't want anything complex, just following main features: 1. Capability to customize color scheme 2. Capability to classify different menu sections (enter, starters, sides , cocktails etc) 3. Capability to display ads (video and images.. activated when idle for 30 seconds or more- should be able to change the idle time for ad activation) 4. Capability to update menus using some sync feature 5. Capability to add multiple restaurants, each with their own account, login and menus which can be synced once they login to the app. Basically the username and password to the app should fetch the menu, ads and UI customization specific to that restaurant. 6. Admin User to manage all restaurants. 7. Restaurant admin to manage the menus and color schemes. I would be interested in buying a ready made app too and then customize it to our needs if someone has a similar product. If you would be developing from scratch, please provide ballpark timelines and cost estimates.