Is this possible with drupal?

Hello People,
This is my first post, and surely, more are to follow. I am a new Drupal user, who just moved from Joomla to Drupal, because Drupal let me do more. :D
I basically have three websites in testing, which I want to link together. So basically, this is a from-scratch project.

Unlike the title of my post, I'm sure that this is possible to do with Drupal. So instead of "Can it be done?", the question changes to "How can it be done?".

Here's what I am aiming for.

I have three websites, one on technology, one on Travel and the third being my blog. Now Basically, I need to link them up, and add new features to them.

1. The Three websites should have a common login. So a user who registers at one website should be able to signin into all three. All websites are on different servers. I know this is possible, and I have seen some websites doing it, but unfortunately, I dont know how to do it. :(

2. I am aiming to make all three websites user-centric. So each user should have a dashboard, which just the first page he sees when he logs in. I wont go into minute details, but basically the dashboard should be the one page with everything the user needs. So this includes a personal manager which can be used to store notes, personal data, a personal calender (different from the main website calender), and a bookmark section which contains marked posts from all three websites. (So there has to be a way to bookmark posts right when they are read). This is a very brief description. Some other details have to be filled, but I can do that as it is almost basic scripting. Also, they should be able to read the posts right from the dashboard itself.

3. a. Each user should have his own profile which contains information collected from the registration form. Also, it should (if posssible) have the option of the user selecting it to be made public or not. The profile should be accessed by entering %URL%/users/%username%/ where the items in %s are variables. I'm sure, we all knew that. :)

3. b. Also, each user should have his own blog, which can be accessed with either the link on his profile or by %URL%/users/%username%/blog. And to avoid overload on the server, the user must first select to start the blog. And the point to be noted here is that the user is able to post only to his blog, which can be accessed with the URL example I just explained. Only the admin (i.e. myself)is able to post to the main websites or any part thereof. Each user should also have a guestbook on his profile where users can leave messages.

3. c. If possible (*I know, what's coming next is maybe too much), Users can bookmark other users, and create a 'friends-list' sort of a thing with mutual approval between the users. So basic social networking features would be great. I can elaborate on this if you are interested.

3. d. Private Messaging should be great.

4. Everything users as well as visitors do should be logged. From pages visited, to time spent on each page, it should be logged.

5. Each website should have a separate forum. Bridging a third party application would be preferable, but the drupal forum module should do if the first option is not possible.

6. A proper user management panel, from where the admin (again, myslf) can access the details of all users, and from the same panel, send e-mails ot notifications to them.

7. As much Ajax as possible.

8. Last, and the most important. The ability to add more websites without any change in the performance of the websites already running.

This is possibly, a very big project, and might even require rewriting of some portions of the core of drupal itself. If you could tell me about what can be done and how, or atleast post links from where I can learn, i would be more than thankful. If third party applications could be bridged to make up for the functionality, I wont mind. Please suggest resources and modules to help me with it.

I actually have a blueprint ready for almost a new platform that incorporates Drupal with many many more features. Basically, it would be like Drupal on Steroids, and possibly, could even be called a fork. But I dont have enough resources or skill to do it alone. If a couple of coding veterans could discuss it with me, we could do it together, and come up with something which would be perhaps the next big thing. But if the questions I raised in this post are completed, I'd progress miles to complete my aim.

Waiting expectantly,
Anurag

P.S. Feel free to message me.

P.P.S. I'm sorry if this is in the wrong board.

P.P.P.S. Once again, this has to be done from scratch. Just thought that I should remind you. ;D