What CSS toolkit for initial page layout do you prefer? Is there is a solution that would have:
There's two widely adopted options: 960 and blueprint. Both rely on a grid-based layout system. This greatly improves the flexibility of your design.
I am not sure about 960 but blueprint also includes a CSS reset. This is something you should be using even if you decide not to go with a CSS framework.
I assume you mean a CSS framework when you say "toolkit".
I've worked with both Blueprint and the 960 Grid System, and they both work well. They are both customizable, and are both modular to some extent.
Overall I found it useful to learn from working with each and seeing what I liked and didn't like, but I've found that there isn't a one-framework-fits-all solution for me. I've created my own base set of resets and styles that I use as a starting point on all my sites and then I customize from there.
Tested cross-browser compatibility could be difficult by a CSS-framework, since the browser compatibility is made up by both the markup and CSS, and to a certain degree the visual design (a webpage has to look right in every browser, since markup and stylesheets have no functionality by themselves to test).
A stylesheet can be as correct as you want it to, but if the markup is bad and doesn't fit the visual design, the compatibility-issue is broken again.
A complete framework for CSS can only provide very basic styling anyways, since it's all up to how you want your design to look.
The best toolkit is no toolkit. I keep around a few templates (a two column page template, a sidebar template, etc.) and use those as I see fit as well as snippets.
My advice: make your own. We all have fonts, sizes and distances we prefer, and only you can know what those are.