[Exim] Compile options - SMP and min processes

We've been running Exim for a couple of years now (now on v4.30), but need
to get a little more out of it. Someone told us that in order for it to
take full advantage of the dual-processor system it is on, we need to
compile it with the SMP option. The problem is I can't find ANYTHING that
talks about an SMP option.

Second, how do you get 10 Exim processes to always stay active? I'll watch
ours start at 5 and then eventually drop to 1. We're running with -bd
-q30m, but I know there must be a default compile option that I'm missing.

Third, is there a way to change the order things happen? First I want to
confirm that the email is for one of our users, then see if it is spam. We
have thousands of messages that come in, get spam checked (wasting DNS
lookups and bandwidth), get virus checked, and then checked to see if the
user actually exists before trashing the message. The first and last need
to get reversed so we can kill the message before wasting more resources on it.

If anyone knows answers to any of these three questions, please let me
know. I'm really getting tired of searching through docs.

Thanks,

Steven Sugg