Hello,
There're actually several sizes, Page size, Interactive size, and a body size. You can see the former two in the properties window if you click anywhere outside of your report body and you can see body properties if you click it and select properties.
You can try that but I have a feeling that it may not help as there is a rendering mechanism in Visual Studio and it can break your report for previews anyway. The question is - do you want to see it unbreakable only for preview or not to break it in a real report? As what you see in a preview is not what you're actually getting after you deploy it to the report server. To see whether it actually breaks it or not, on a preview page you can find a little button called "print layout" and that will show you exactly how it will be printed.
good luck,
yurich
