I am glad to see some more ambitious initiative coming from Italy. Italian culture is not really entrepreneurial (I've spent the past year in Como). That would explain the "one founder" issue you're having.
I like the questions you are raising. I have written about them before and have started playing with my own approach. It is a big project, but unlike yourself, I would not be concerned much about applying to YC with it. YC is not a research incubator but a business, and no matter how cool the people seem to be, they're after the money. Nothing bad, it's just capitalism. YC makes most of the money from the VCs, so they need you to have something that will sell (to VCs). It's a very smart business model that they're running.
If you are really passionate about these issues, you need to build a prototype or specification and throw it out on the web as an open source to get support. I see the possibility of a viable business model in the authentication scheme.
That said, I disagree with your approach to tackling the problems you listed. Your issues are valid, but not the most important. You have not identified the core problem. Consider this. You publish something on the web, the website goes bankrupt or decides to shut down. Your data goes down with it. Your article, your comment, your photo, blog post, this comment I'm writing. We've given all the power of data preservation to the web sites. The web is not preserving it self. If we see it at the biggest library of all, just imagine this, every day a part of it gets burned down.
Making data independent of servers will solve most of the issues you raised. Your address book and contacts belong to servers and web apps, as you said, so you don't manage them. If you were to own the data yourself, and the webapps only managed and used your data, you would have a single point of authentication, single address book, single stream of your produced content.
Think of the desktop vs web app paradigm. We need a platform for applications on the web that will be based on user content. You own your data, but the webapp only uses it to add functionalities. You install a webapp onto your data just as on the desktop. You delete an application (or detach from your data). This would be a new paradigm of the web, where all the control is with the user, the user base is unique on the web without clustering, and applications are just that.
Emails are nothing else but user generated content. We tend to see it differently, but it is absolutely the same, the servers own it. I wrote recently an article about emails describing how much we don't have control over them:
http://www.aleveo.com/ideas/decentralized-email
You do not own your emails. The problem I want to stress is that, as long as someone else owns them, you don't. If no one owns them, you might claim full control. It is the benefit of decentralization.
If you take a route of making another central point of aggregation and data control, you have simply contributed the system you want to change. I would suggest you start thinking in the decentralized direction.
As you said, the web has issues, but you can't build on top of it if you want to change, you need to go lower.
We can take this further if interested dejan dot strbac at aleveo dot com, I will publish the whole thing on www.aleveo.com when I am done with the draft.
I wish you much success with the YC application, I couldn't agree more that such fundamental projects need to be supported rather than useless web bubbles.