Website development and improve existing IOS and Android Apps. - App project

Mobile app project description

Looking for a new partner to improve the IOS and Android apps and develop a Website.
For apps we use (Swift and Java). Also, we are using Symfony Framework (on PHP 7.2) as a Server Side Application, as it's a well known, and already a standard in developing complex web projects. It's very flexible, reliable and it has a big community and long-term support. As a database we are using MySQL or MongoDB. API is documented with Swagger.
Rest will be discussed.
REQUEST FOR INFORMATION
1. Experience with above stated technologies for company & likely individuals working on this project
2. Tentative development timeframe
3. Approximate cost
4. Ability to be flexible with engagement models like fixed price with milestones
Once you provide us with the above information and we complete the first round of shortlist, we will sign an NDA and share the UI design and freeze the requirements.