Emin,
I cannot comment on your choice of machine as I have never owned or seen it work.
As for chemicals, all this will become clearer at the Prochem Training course, but as a guide if you insist on Prochem only.
Traffic Lane pre-spray maybe Multi-Pro or Traffic Lane Gold for Wool, followed by Fibre & Fabric Rinse in the tank, for badly soiled carpets maybe Crystal Green/Double clean in the tank.
Solvall spotter, Stain Pro, Citrus Gell. for any stain removal, all depends on the stain you want to remove.
But as I say you will learn all these things on the course, some jobs may require different methods.
Phil