Sonoma to Sequoia upgrade, please advise

Hi,

I have an iMac w. M3 chip purchased in 2024, 8 GB memory and only 2 ports; runs OS Sonoma 14.8.7. 

I am preparing to upgrade the OS to Sequoia, as I do not care for any new features or functionality, not finding anything and new bugs coming with Tahoe, but I need security related patches.

I use only the following 3rd party SW: MS Office 365, CCC, Print Window, ZOOM, MalwareBytes, Firefox, Photo Transfer, Go to meeting

External devices:

- HL-L2370DW(XL) Brother printer

- Epson Perfection V600 Photo scanner

- two disk drives for TimeMachine and CCC backups (Seagate Backup Plus Ultraslim)

- APC UPS

- Xcellon 7-port powered USB 3 slim aluminum hub that supports: printer, UPS, wired keyboard, the CCC backup drive, scanner.

The wired Macally mouse is plugged into the keyboard.

Please let me know the following about upgrade from Sonoma to Sequoia:

1. Will the KBD shortcuts be saved?

2. Will the browser plugins work (in Firefox and Safari)?

3. May I assume that mail folders will not be touched and all mail settings will be saved (I am using POP and have all my emails on my computer)

4. May I assume that all Firefox bookmarks will be saved?

I am not a technical user and as a result all upgrades are a very stressful event for me because many times I wake up with problems I do not know how to deal with. Is there anything I should be aware of in terms of what to expect, do or not do to avoid problems?

Thanks in advance.