MacBook Air early 2015 running Mojave (10.14.5), should I update to 10.14.6 first or should I immediately upgrade to Monterey?

[BismaBRJ]

(Note: where I live, decimals are denoted with commas rather than periods (primary language set to English, region set to Indonesia). Any numbers I type out are from what my Mac displays, so I'm sorry for any confusion)

As per the title, I am currently using a MacBook Air early 2015 (11-inch, with 128 GB storage, 4 GB RAM) running macOS Mojave 10.14.5 with no issues. I currently have around 20 GB of free space, but of course I can attempt to clear out more disk space with backups etc.

In "Software Update" in my System Preferences, I see:

• an update available for my Mac: "macOS 10.14.6 Update", taking up 2,64 GB and ready to install (apparently it had been downloaded in the background without my knowledge); and
• a prompt to upgrade to macOS Monterey 12.5, with a 12,4 GB download (and I heard that installing that for Mojave requires 26 GB of available storage according to Apple).

My questions:

1. Should I consider upgrading to Monterey at all?
2. Let's say I'm planning to clear up that much space to download AND install Monterey.

• a. Does that mean I need to free up a total of at least 38,4 GB (12,4 GB + 26 GB) of storage space before even pressing that download button? Or is it only 26 GB in total?
• b. Seeing that I have two update prompts (10.14.6 and 12.5), if I want to eventually get to 12.5, should I just completely ignore the 10.14.6 update (since it's a waste of precious 2,64 GB of storage space) or is it somehow wiser to update to 10.14.6 first and only then 12.5?
• c. The classic question: do I get any of that storage back?? Or will I lose up to 38,4 GB of space after the upgrade (since "System" will use up all of it)?

I don't really have an urgency to upgrade to Monterey other than missing out on newer versions of some applications (and all of my applications are already 64-bit). Thank you.

EDIT: attached screenshots of my update/upgrade prompts because why not

 

[Nermal]

My personal opinion is that you should only move to OS 12.5 if you actually need it. I find it to be full of bugs, and it would probably be relatively slow on a 2015 machine. If you do choose to install it then there is no need to 'step' to 10.14.6 first.

If you're happy to stick with 10.14 then by all means install the 10.14.6 update.

I can't answer your specific questions around space as I don't let my systems get that full.