With regard to the specific technical skills you need, that will depend on the nature of your application - functionality, performance requirements etc - and on your own skills and preferences. You also need to consider things like reliability, security, maintainability, availability of documentation and support (advice and skills), deployability, scalability, and so on. If your project takes off, how easy will it be to hire extra help, modify the app quickly and reliably in response to customer requests, move to a more powerful server, ramp up to large numbers of users etc?
All of these factors are good reasons to look at using standard tools (ideally free open source options) where appropriate. There is a lot of good open source software out there that will give you a lot of standard functionality and features for free, based on well-tested and familiar technologies and design principles e.g. MVC web frameworks for different languages like Django (Python), Rails (Ruby), Grails (Groovy), Spring Roo (
Java) etc. If one of these will suit your application, then it will increase your productivity, improve the robustness and flexibility of your application, and make it much easier to find help from people who already understand the platform. You would obviously need to code your specific functionality yourself, but at least you get all the other stuff for free. You can customise your browser interface using HTML/CSS, JavaScript and more great free libraries to give you the user experience you require.
Also, is it the kind of application you could build and deploy on a cloud service e.g.
Google App Engine,
Amazon EC2,
Heroku etc? If so, this would take care of a lot of concerns over reliability and scalability of the underlying platform, but you would need to explore the cost implications for your application in terms of processing requirements, number of users etc. (Google App Engine is perhaps less flexible here, as it ties you into a custom application framework and data store).
As an aside, I'm currently working my way through the
O'Reilly School of Technology Python courses, and I've been very impressed with the quality of the materials and of the expert tutorial support (unlike most commercial online training courses). They offer similar
courses in a lot of technologies relating to web development, so this might be an option to help you acquire the specific tech skills you decide you need for your project. There are also some free options for learning about web app development e.g.
Coursera.
You might well be able to learn this stuff and build at least a working prototype for your application alongside a reasonable day job, although when you are ready to move into production you would probably need to devote yourself to the task full time (and more!) and maybe look for some expert help. My own limited experience of working in a tech start-up was that the technology and system development were the easy bits - securing finance, finding customers, giving them what they want (or convincing them they want what you have to offer!) is the really hard part. On the other hand, the availability of free, high-quality software tools and the advent of pay-per-use cloud platforms mean that many of the costs of developing and deploying a web application are far lower than they might have been just a few years ago.
As for the practicalities of creating a technology start-up, does your university have an office dedicated to such projects? Many colleges launch "spin-off" businesses, so you may be able to get advice on this, although obviously you want to guard your intellectual property carefully. Before you start talking to people about the details of your project, you should probably get some legal advice on
non-disclosure agreements, for example.
Incidentally, you might be able to find e.g. some kind of Master's course that would teach you some web development skills and allow you to work on your project for your thesis, but you might also find the college would automatically own the commercial rights to your software: some colleges might be happy to waive these rights in advance, but if your idea is really smart, they might be less keen to let go of it!
Finally, if you can find a way to keep your "regular" work ticking over as long as possible while you work on this (if only to ease the financial pressure), I should think having the experience of building not just your own application but your own start-up business would be extremely marketable, especially given your existing advanced qualifications and experience.
Anyway, best of luck with your ambitions.