[Richard Crowley]

"Mrplow350" wrote...
We are trying to take audio from the upstairs of a church and bring it
downstairs. The upstairs has all of the out puts you can imagine
including XLR, Mini, and RCA. That upstairs system is very powerfull
with several amps. The downstairs is smaller but has 2 large speakers
and about 5 XLR inputs.

So we are assuming that the "upstairs system" has a mixer and several
power amplifiers. And the "downstairs system" also has a mixer, amp,
and speakers.

What cable is type of cable is best used (like gauge if something that
need to be made)

As others have already recommended, a shielded, twisted-pair cable
is typically used in this situation. This is the same kind of cable that
is likely used to interconnect other pieces of equipment such as
between mixer and power amplifier(s), etc. It may even be the same
kind of cable used between the mixer and the microphone jacks at the
front of the church, etc.

and what connection used to take the sound from upstairs and put
through downstairs amp?

That is actually a much more critical question/issue than what kind of
cable to use. Since you didn't reveal the identity of ANY of the equipment,
we can offer only nearly-useless generic advice to find "the appropriate
output" from the source mixer. It seems doubtful that you could discover
which connection this is without a bit more hard details and expertiese.

It is about 100ft run at the most so is there a signal loss?

Assuming you are using XLR (i.e. balanced) output at the source end
and input at the destination, it is of no concern whatsoever. 100 ft is a
very modest distance to send balanced line-level audio. Our grand-
parents used to send similar signals hundreds of miles over un-shielded
pair. That was how radio networks were implemented before microwave
and satellite.

Note that if you want specific advice that you might find useful, you
must reveal the exact make/model of the equipment at both ends.