I understand on the ability of reply, some of the browsers in their different versions do not work well with live chat.
On the contactor, I would suggest the Eaton C25BNB240A over the other. Rating is good for application and should give a good longevity as their products are very good.
On the disconnect, you could use that one, or just install a plain 20 amp double pole switch
to use. If the circuit is going to be 30 amps, they make a 30a double pole as well.
Now, if the breaker panel is in a line of sight of the contactor, you do not need the shutoff between, but if not, I would just use the switch for working on the contactor.
The dust collector, if plugged into a receptacle, does not need any cutoff itself, as the plug and cord is allowed by code for it to be the disconnect on maintenance.
Let me know if anything else is needed.