New User to a UPS

[HellStunter]

Hello guys,

Today I received my APC Easy UPS BVX2200LI-IN , for my PC and two monitors. My PC configurations are: 

850 watt PSU,R9 5900x, RTX 4070TI, 9 NZXT ARGB fan and the general stuff like Nvme, hdd and all.

I also have a home inverter but it can't take the load of my PC that's why I bought this UPS.

My question is, if I'm not using my PC, should I always keep my UPS plugged in to the power source? If yes, how much will it affect my electricity bill? I do switch the UPS off, but should it be plugged in all the time?

What do you guys do at your home with your UPS. 

Other question is:

Should I keep both of my monitors connected to the UPS, will it be able to take to load for at least 5 mins, so that I can save my work and shut it down.

Thanks in advance!