We use Similac Advance, 2-3oz every 2-4 hours. Distilled water with bottle warmer. My first was ok with room temp but this baby makes lots of faces since he was breastfed longer before the switch whereas my first was pretty much on room temp formula from the start. Temperature is just a preference, totally safe but I’d not do anything cold until 6 months or so. As far as boiling I think it depends on water quality in your area, city vs well water etc. We live in an urban area and although it’s “safe” I feel more comfortable using purified or distilled water.
The hospital suggested boiling the water and adding the formula right when it started to boil to get rid of any contamination. With all the recalls that's what they suggested. Who knows if it's truly necessary
I use kendamil as well with room temp, I do warm it up in the bottle warmer for about 2 minutes and it gives it just a little warmth! I’m bf and only giving my son extra 2oz of kendamil he’s still hungry.