What software should I integrate to handle the credit card payment on my app?

Yes Wix supports a mulitude of APIs to used for various fetch calls for your web pages. If you already have to API's in mind you can venture off within you WIX code to integrate within your application's processes. There shouldn't be any complications getting this done. Please see the link below for more information https://www.wix.com/code/home/api

Create an ideal customer profile. Create some questions that will allow to you survey a potential tester to determine if they fit your profile. Design simple landing page with very clear value proposition that speaks to your ideal customer. Ask for a minimum of information up-front (email), but ask for more info after they commit by submitting the first piece of info. (KISSmetrics does a good job of this on their current website trial signup). Use the their answers to these profiling questions to put the applicants into buckets. Let in the most ideal bucket first, or split them into groups if they're big enough. Try and measure engagement the best you can. Measure qualitative and quantitative data. Schedule calls with your beta testers to find out more, especially with the ones who's user behavior seemed to indicate that they didn't get value from your product. Find out why. Make sure they are indeed your ideal customer. Pick up the phone and get to know your customers inside and out. Meet them in person if possible. Incorporate their feedback quickly and get more feedback. Rinse repeat.

If I was just starting out, I'd consider learning Meteor (https://www.meteor.com/). It's just entered version 1.0 and after working with it for a little less than a year I do have some issues with it but it still makes for a very solid framework that gets you up and running very fast. You would only need to learn Javascript, and you can slowly work your way towards nodejs from there (which Meteor is based on) if you want to, or you could get the basics down and focus on learning design if you prefer.

Having gone through this multiple times either in new startups or for side projects, here is how I would approach turning your idea into an app. 1. Defining the Minimum Viable Product Your first goal with any new idea should be about proving the idea and finding a market that wants the app you want to build. Achieving that quickly is probably one of the most important thing. To achieve that, you will need to write the specifications that will constitute your MVP. The MVP is basically the simplest expression of your idea to prove it. This step should not cost you much as you can do this on your own. 2. Design the app Before starting any development work, I would suggest you work with a good UX/UI designer to create wireframes and mockups of the app based on the specifications you came up with in step 1. You can find good designers in meetups & hackathons or on website like Dribbble or 99designs. If you want to reduce your costs, you can give shares in the project to the designer. Otherwise, it really depend on the size of the MVP but I would say it will probably cost between $5K-$10K. 3. Develop the app Once you have the specifications and the design of the app, you now need to find a good developer that will build it. Again, you can find good developers in meetups & hackathons or on sites like Github. If you want to reduce your costs, you can give shares in the project to the developer. Otherwise, it really depend on the size of the MVP but I would say it will probably cost between $10K-$25K. For this part however, I would recommend the developer becomes part of the project as his engagement will most likely be higher. 4. Test the app This step is not only about making sure the app is bug free, it's also making sure the app does what was intended in the specifications. To test the app, you can use platforms like BrowserStack or SauceLabs which gives you access to multiple devices/browsers. You can do this step on your own so the cost will be for the subscription to the test platform which would be around $100/month. Hope this helps and good luck with your project.

If you are aiming on iOS and Android with Windows Phone 7/8 as a plus you should use C# as the language and Xamarin Studio as the IDE/Framework. You may also choose to use Visual Studio on Windows as an option. Take a look on their website: http://www.xamarin.com Even Microsoft is using Xamarin to build iOS applications and they have over 400k developers using it. Your application will be native (compiled to the platform you choose) and you are able to use all the native libraries, widgets and UI parts. You will need a cross-platform architecture to be able to reuse code among platforms and using Xamarin you may be able to reuse more than 50-60% of your C# code among platforms. This solution may render the same experience on the devices as on the website, but it enables your applications to deliver much more performance and features than any HTML5 solution. Facebook went from HTML5 to native applications due to performance and user experience limitations (gestures and other platform features are not present using HTML5).