migrated system with new urls

I am switching system from a MVC to a custom code system. Currently we are using this format for urls:

Best practices for withstanding launch day traffic burst

We are working on a website for a client that (for once) is expected to get a fair amount of traffic on day one. There are press releases, people are blogging about it, etc. I am a little concerned that we're going to fall flat on our face on day one. What are the main things you would look at to ensure (in advance without real traffic data) that you can stay standing after a big launch.

Why use deflate instead of gzip for text files served by Apache?

What advantages do either method offer for html, css and javascript files served by a LAMP server. Are there better alternatives?