Configure Apache with FastCGI External Server

Sorry it is more like an apache question than a FastCGI but since they
often work together I thought I can get some good advice. 

We have Apache 2.0 server running on Solaris 10 (2 processor 64 bit
SPARC). The server runs only one instance of Fast CGI binary app written
in C and configured as external server started independently from Apache
server. The app is multithreaded with thread pool of up 100 threads. It
services very memory and CPU consuming requests of delivering very large
files. 

What's the best way to configure Apache server? I am not an Apache pro,
but our network guy told me it is compiled as threaded MPM with up to 64
httpd processes and two threads per process. My understanding was that
in threaded MPM there is one process that spawns multiple threads. Will
it increase performance and reduce memory and CPU usage if we configure
it to use only one process? 

Also will we benefit if we upgrade to latest Apache 2.2?