> 1. Which Linux is most like Unix (BSD)?

Perhaps take a look at slackware, it can be run with a bsd init.
Is has some things in common with freebsd.

> 
> 2. Could NetBSD do anything Linux does? I assume that I would build the
> kernel with Linux and ELL32. Would I also need a compatibility package?

If you want to run a server, well, in that case, linux still got to grow a lot.
But it really depends what you want to do with it.
If you are more specific what the server must do, then it would be easier to answer.
Bye,

Mipam