David,
You may wish to design your processing area to avoid cross contamination
of alt-process chemicals with negative chemicals. This is especially
important for pt/pd processing. Use separate trays and a large sink.
wash the sink after each type of processing. Or if you have the room,
use two sinks. I built a 10 foot by two foot sink out of wood with
caulk and epoxy paint. This is a good size for using 13 by 18 inch
trays (11x14). It is a bit tight but manageable for 16x20.
Have a table for coating as far away from the sink as you can get it.
For ventilation, remember to have a louver for air to enter the room.
(Any vent fan will only work with air coming into the area.) A good
place is the opposite wall from the sink with the vent behind the sink.
It is a good idea to have air flowing over your coating area as well.
(However, wearing a dust mask when drying or handling powered chemicals
is still a good idea.)
And, definitely invest in a sodium vapor safe light.
Jeff