Help and advice needed with my first UPS (questions and concerns)

[Euphoria]

[Solved. Never mind, I found the answers eventually around other forums and from asking different manufacturers of UPS.]

Hi everyone, due to a huge number of power outages I've purchased my first UPS. This is the UPS: Legrand Keor SP 2000VA (1200w) - it's entry level nothing special, but the reviews were good, price was reasonable, I've owned Legrand products and never had issues with anything, and it can power my rig for long enough.

 

My questions and concerns:

1. Got the answer to this from another UPS manufacturer; Apparently this buzzing noise is from the transformer/s and is perfectly normal unless it's an inconsistent sound; like buzzing louder then getting quiet then loud again, or a crackling sound.
   With the batteries fully charged, all connected devices and the UPS itself powered off the UPS continues to buzz until I unplug it from the wall. I've checked the fans inside the UPS and they're not spinning so it's not them.
   Is this normal for some UPS? I've never owned any electrical device that still buzzes when it's completely off.
    
2. Found the answer to this from asking on other forums; this is normal as internal components still have power running through them even when nothing is being powered, it basically means it's poised and ready to go all the time, they don't go into standby. The temp can vary from UPS to UPS, but as long as it's only warm to touch and not hot or giving off any burning or nasty smells, it's fine. Also, the batteries need to stay under 35-40c or decay will be increased and replacements will be required more frequently.
   While plugged into mains power, the batteries are fully charged, and no devices plugged into the UPS the top of it is still quite toasty (I would say roughly 35-40c), it's definitely not hot but my cat wants to make a home on top of it, put it that way.
   Again, is this normal even when it's not in use or charging?
    
3. Found the answer to this; UPS should not be unplugged or power cycled regularly, they're designed to be on 24/7 so frequent cycles like unplugging them every night will reduce the batteries life span.
   Once the batteries show 100% full according to Windows and the UPS software, if I switch off the UPS and all devices, disconnect everything from the mains, leave it for 2-3 hours then turn it on again the batteries read around 90% full. So, if this is correct the batteries lost -10% charge in just a few hours while doing absolutely nothing.
   Is this Windows and the UPS software being derpy or a normal battery/UPS thing?
    
4. Found the answer to this too; apparently UPS should always be connected directly to a mains outlet and never through a extension or multiple socket adapter. But a longer IEC C13 cable can be used if needed as long as the cable is high quality and the correct gauge.
   The final thing is a sort of setup question - at the moment my work area is in our bedroom until I finish renovating the room that will be the office. My question is for a month or two would it be safe and OK to plug the UPS power cable into a multiple socket extension cable that has its own surge protector built in?
   With the temporary setup being in our bedroom and the UPS giving off a buzz it's annoying during the night so I have to unplug it from the wall, but getting to it is a major hassle so I want to run an extension from another outlet that I can get to more easily to unplug it at night. I just wondered if having the UPS drawing its power through an extension cable with it's own surge protector might cause issues?

I think that's all my questions at the moment.

Thanks, appreciate any input.