Open up your /etc/fstab in an editor (nano -w works fine) and make sure you a line exactly like this in it:
none /proc proc defaults 0 0
I don't really know but it's possible that you would get a more verbal error if the kernel can't find where to mount /proc so I don't really know if this is the problem.
As for the symlink - if you emerge the 2.6 Gentoo kernel sources you will get a symlink called linux-beta in /usr/src. It doesn't really do much. The linux link in that same directory is important when building other packages that depend on the kernel source (like device drivers).
You might want to search the Gentoo Forums
for information about the kernel stopping at "Mounting /proc". I have never come across it myself. But anyway, bookmark the Gentoo Forums, there is a wealth of knowledge there, both Gentoo-specific and general Linux stuff.