Integrating home page with WordPress

I’m very new to WordPress. I’ve installed it, chosen theme, and integrated my photo gallery into it. I have an existing home page and a few other “static” pages that I’d like to blend in with the WordPress pages. I think I understand about changing the CSS of either the home page or the WordPress to make them similar visually.

But I’m not clear on best way to include existing web pages. I like the dynamic part of WordPress for the links to pages so is there a way I can migrate my pages to WordPress without losing my layouts (not the menus, footers, etc. just the main part of the page)?

E.g. I like my home page just the way it is (originally created in GoLive), but I’d like to include WordPress’s menu links on top. Is there a PHP statement to use to include those menus? Do I include my original CSS in the page?

I think this is just a matter of someone explaining this so I can “get it”.

Thanks for any help. More questions to follow I am sure.