Questions about powered formula feeding!

Is it true that you have to boil water or use warm water when mixing it with powered formula? I have been using room temp bottled water to mix with powered formula all along... is that ok? I read that powered formula isn’t sterile or something.

Also, after I have made a bottle (powered formula), can I immediately store it in the fridge then take it out later (say 2-5 hours) for use? I know once made, it is only good for 1 hour once it’s out or at room temp.

And is it ok to put a made bottle (powered formula) into a bottle warmer machine to warm up the bottle before feeding to baby?

And if I were to use the bottle water, do I warm up the bottle with just water in it first then add the powered formula or can I make the bottle with the formula first then warm it up??

I’m very new at parenting and have been ff and just need to know if these things are ok or safe to do. Thank you!