Belt Furnaces from Italy

We manufacture gold and silver medals, with religious saints engraved
on it. We just bought a Belt Furnaces from Italy. (IECO) Right now
we are doing some testings with the machine but we have some problems:

Our Gold solder does not cover all the medal in order to solder it
with the gold plate that goes at the back (since our medal is hollow).
Before we got the machine we did these kind of process by hand so we
actually put heat on the part we want it to sold and the solder flow
to the heat, but this machine reachs more than 1000g. celsius and the
band that carries the medals into the furnace reach 300 cms per minute
so we need to know some things:

1.- Which is the melting temperture for the 10,14,18karat gold?

2.-Is it the same melting temperture if the gold is not moving than
if it is moving through the band?

3.-We are using gold strips but we think it would be better if we
use gold dust instead, what do you think? We know that there is gold
solder in paste but is only for low tempertures.

thank you very much for your time, we will be wainting for your
opinion

Carlos Reyes