Or is it better to do noise reduction at a later point in the work flow?
It’s far better not to do noise reduction. Go > Utilities > Activity Monitor. Find out what’s taking up all the resources. It’s not normal for MacBooks to crank up their fans periodically. Restart the Mac and make sure none of the background services (Skype, iCloud) starts. Disconnect the network and turn off WiFi, Bluetooth, Location Services, etc. etc.
I haven’t heard anyone ducking the background music in a long time. I think they stopped doing that in favor of leaving the background music in the background for the whole thing. Sometimes, producers time it so the background music stops at the end of the show. They bring it up as a signature farewell. Of course that means you need to plan the show.
And listen to it. If you don’t have good speakers anywhere in the house, then good headphones are required. I mean actual sealed headphones, not earbuds.

There’s nothing like comments about having that funny noise in the background of your podcast… and you can’t hear anything.
In what order should voice efx be applied?
Um. Don’t do anything to it? There’s two problems with presenting an effects laundry list right at the top of the production. You have to do it at each and every show and that’s going to get tired about the fourth or fifth show. And, of course, you can’t make any mistakes.
Also, you’re building in work that may conflict with rescues. If you have to apply a notch filter and noise reduction for an interview, which order do you do it?
Export WAV (Microsoft) sound files of each live recording. Put them in a safe place like a stand-alone drive or maybe Thumb Drive. There’s just nothing like having Audacity go headfirst into the dirt and take the only copy of your show with it. Do Not use Audacity Projects for this.
There is one effect that’s pretty much normal for spoken word podcasts: leveling. We published Level Speech to do automatic voice compression and management.
https://wiki.audacityteam.org/wiki/Nyquist_Effect_Plug-ins#Level_Speech
Let us know how that works. I do leveling using older tools and the AudioBook Mastering Suite uses yet a different collection of tools.
Fair warning. Nothing signals a nine year old trying to do a podcast than room echoes. The current fashion of bare wood floors and plain white walls is a Hostile Recording Environment.
http://kozco.com/tech/audacity/clips/EchoSample.mp3
You might better record in the garage.
I know someone who regularly cranked out good quiet voice tracks and I couldn’t figure out how he did it.
He was recording in his car.
This is me writing that down.
Koz