Hey thanks for taking the time out to post in the forums! Welcome 
I’m not a current Hubitat user, but I’ve read through a lot of these threads and think I know the answers to most of your questions – I’m sure others can pitch in if they’re incorrect.
From my understanding, you can now update the firmware via @bcopeland’s firmware updater which instructions can be found here: [RELEASE] Hubitat Z-Wave Firmware Updater
No, once should be fine.
Yeah, there are some known issues that have been fixed that are currently in the market right now. The two biggest ones would be:
- Dimmers: If you setup notifications and they’re active, they’ll be dismissed if you use the switch to dim
- On/Off: In rare cases, the device fails in a 3-Way setting to detect using a dumb switch and you’ll notice that On/Off gets out of sync – we’ve added a manual option for configuration if this happens
Notes on what have been added/fixed can be found on the firmware pages:
- Black Series On/Off: Knowledge Base Redirect – Inovelli
- Black Series Dimmer: Knowledge Base Redirect – Inovelli
- Red Series On/Off: Knowledge Base Redirect – Inovelli
- Red Series Dimmer: Knowledge Base Redirect – Inovelli
This one I’m not sure on – I believe the answer is no, but @harjms or @BertABCD1234, or @EricM_Inovelli would know the answer here better.