1. where are your developers and engineers located?
One common trait among mobile development firms is to place a liaison to the development team in a particular market to claim the company is "local". But in reality, the designers and developers would be based in another country. So be sure the company which claims it is "local" actually is.
2. What are the project costs, as well as future updates?
Obviously, you'll want to have a clear idea as to the total project will cost. Mobile app developers might not be able to give you an exact figure before they start to work on the app, but they should be able to quote reasonably based on their experience. Also, make sure the developers provide you with updates, as apps can become obsolete within a matter of months.
3. The platforms and the company’s experience?
You'll have to determine if your app will be available for Android, iPhone, Windows, and/or Blackberry devices. If you want your app to be multi-platform, get the cost estimates beforehand. And make detailed enquiries regarding them before you commit yourself.
4. How will users be able to download my app?
Beyond building a user-friendly website, you must also know which third-party sites will sell your app to the end users. Also, if you want your app available on iTunes, and the mobile development firm can’t give you a reasonable guarantee that it will be approved, then that is not a company worth its name. Just move on.
5. of all the company’s previous projects, which one(s) are you most proud of and why?
Mobile app development companies, like everybody else, will want to showcase their strengths, so they will show you what (they think) their best work is. If what is shown doesn't seem very appealing to you, then you should think long before signing them. This is because it's often more easier to design a goody-goody app than to create an effective, functional, user-centric app. A good thumb rule for an effective app is that it should be easy for your mom to use.