Deprecated - Performance and scalability

A friend of mine doubts that Drupal can scale and so I wanted to hear from any on here on their real experience on very large websites. Can Drupal scale >1million users without issues?

Thanks so much!

I need to insert a form into a page (along with some javascript) but Drupal strips this permanently. Does anyone know why it's doing this and how I can fix it?

If not, can anyone think of a different solution?

When I add styles to my text the style shows up in the editor, but does not show in the posts page. When I check the source code of the post it does not show my styles around the text where I put it... but if I hit edit and am back in the editor the code is back!

This problem doesn't have anything to do with tinyMCE because I had the same problem before I installed, during, and when I disabled it.

Why is drupal stripping my styling from my posts? Does anyone know how I can fix this?

I'm new at Drupal, but this is the first real snag I've run into. It's derailing me!

The following code snippet is from ecommerce/product/product.module:

A site that I am working on currently has 400 entries with 700 comments and less than 10 users. The amount of content in that area of the site will double or triple over this year. In addition to that steadily growing content, I'll soon be allowing user registration and adding the following features: organic groups, detailed user profiles, user blogs, e commerce, and a calendar. If I'm using a module like boost on this site, are there any pros or cons to breaking the site up into multiple databases?

I just want to say that I was dugg today [ http://anabubula.com ] and Drupal 4.7 gave its best :-)
In one hour my server had more than 24.000 visits and Drupal had a very smooth reaction showing which is the best CMS ever :-)
Before 2 days I made the change from the buggy MT's GridServer to a dedicated server at SoftLayer and after this movement
dugg was come ;-)

The next step now is to move from 4.7 to 5.0, hopefully at the end of this week...