1. If you want an easy distro, go with Mandrake.
2. I believe if your referring to the package management, the only one that I can think of that uses Portage is Gentoo, since they created it.
3. Compiling depends on the system really and what you need on the system.
4. Any distro is as secure as
YOU the administrator makes it.
If I was you and your server is on the lower end, and you want the Portage Tree, then go with Gentoo. You basically install what you want during the initial install of it, but its not easy as some of the other distro's out there. Your actually asking for things that no distro really has over the next.
And this also should belong in the Distro section. You might want to check out
www.distrowatch.com and maybe make this decision for yourself. Your only going to get opinions asking these sorts of questions.