lost /usr/bin/emerge

[curmudgeon]

Installing first gentoo system.

Underestimated disk space that a basic system would take. Used Partition
Magic (8) to rearrange disk space. Rebooted system and attempted to add
another package. Received "permission denied" error.

Looked at /usr/bin/emerge file. Saw permissions "000" and file length of 0.

1. How do I recover (completely)? I assume I should get a temporary
emerge and re-emerge portage.

2. Does some way exist to check the rest of the system (the packages
that portage installed) for possible filesystem corrpution?

Thank you.