Wet location does NOT equal dust proof.
I'm willing to give a NEMA 4 gasketed enclosure the benefit of the doubt, but the usual NEMA 3R 'raintight' stuff is rather good at getting filled with sawdust.
Motors ought to be TEFC- though, again, I'm willing to accept factory motors on the machinery. I'm willing to trust a saw maker to know something about making saws.
Dust collection is a bit touchy. As a commercial-size shop, the system is likley large enough that you will need to use metal duct and ground / bond the pieces together.
Not all sawdust is a hazard. The coarse dust from the table saw is not as troublesome as the fine dust from the sander, and the wood chips from the planer are of very little concern. Varnish and paint -be they solvent fumes, overspray, or sanding dust - are a very serious concern.