You wont need any extraction system if you use non leaded enamels.
If you can fined leaded they are great, but do need proper
ventilation to use them, not in a closed w/shop in winter!!..
You will need the kiln some way away from where you do all your
preparation work. As you will gather, the firing is really the last
part of the enamelling process, unless you plan to fire several
times on each piece.
However, I started enamelling using only a 1in dia propane torch and
normal air, not blown as in compressed. This did all the enamelling
I needed till I got a kiln for much bigger work, some enamelling that
needed a kiln, like counter enamelling.
Where you will need extraction is if you plan to use a band sander
to finish the edges of copper as this will produce dust, not good for
your lungs!!. Also the finishing, like polishing edges etc. This
also needs an extraction system. Preferrably vented to the outside.
I mention all these things as its fine having enamelling as a hobby,
but to earn a proper wage per hour via making and selling, thats a
different ball game.
Get back to all of us here with a much more detailed plan of
operation then we can help you get it right first time!!.